docs: update documentation

[yoshi-automation]

This PR was generated using Autosynth. 🌈

Commits in this repo since last synth:
3adb76e chore: release 0.125.0 (#2661)
42ad09a test: fix broken system test (#2688)
4418059 feat: add ServiceMonitoringServiceClient; update clients (#2668)
d89b430 feat: update required version of google/cloud-core (#2687)
d8cd161 feat: add getPrivateProperty test helper (#2686)
bc27230 fix: update metadata (#2680)
f6884af feat: introduce security center v1p1beta1 (#2681)

Log from Synthtool

synthtool > Executing /tmpfs/src/git/autosynth/working_repo/Bigtable/synth.py.
On branch autosynth-bigtable
nothing to commit, working tree clean
HEAD detached at FETCH_HEAD
nothing to commit, working tree clean
synthtool > Ensuring dependencies.
synthtool > Pulling artman image.
latest: Pulling from googleapis/artman
Digest: sha256:6aec9c34db0e4be221cdaf6faba27bdc07cfea846808b3d3b964dfce3a9a0f9b
Status: Image is up to date for googleapis/artman:latest
synthtool > Cloning googleapis.
synthtool > Running generator for google/bigtable/artman_bigtable.yaml.
synthtool > Generated code into /home/kbuilder/.cache/synthtool/googleapis/artman-genfiles/php/google-cloud-bigtable-v2.
synthtool > No files in sources /home/kbuilder/.cache/synthtool/googleapis/artman-genfiles/php/google-cloud-bigtable-v2/proto/src/Google/Cloud/BigTable were copied. Does the source contain files?
synthtool > Running generator for google/bigtable/admin/artman_bigtableadmin.yaml.
synthtool > Generated code into /home/kbuilder/.cache/synthtool/googleapis/artman-genfiles/php/google-cloud-bigtable-admin-v2.
synthtool > Replaced "'serviceAddress' =>" in src/Admin/V2/Gapic/BigtableTableAdminGapicClient.php.
synthtool > Replaced "'serviceAddress' =>" in src/Admin/V2/Gapic/BigtableInstanceAdminGapicClient.php.
synthtool > Replaced "'serviceAddress' =>" in src/V2/Gapic/BigtableGapicClient.php.
synthtool > Replaced '@type string \\$serviceAddress\\n\\s+\\*\\s+The address' in src/Admin/V2/Gapic/BigtableTableAdminGapicClient.php.
synthtool > Replaced '@type string \\$serviceAddress\\n\\s+\\*\\s+The address' in src/Admin/V2/Gapic/BigtableInstanceAdminGapicClient.php.
synthtool > Replaced '@type string \\$serviceAddress\\n\\s+\\*\\s+The address' in src/V2/Gapic/BigtableGapicClient.php.
synthtool > Replaced '\\$transportConfig, and any \\$serviceAddress' in src/Admin/V2/Gapic/BigtableTableAdminGapicClient.php.
synthtool > Replaced '\\$transportConfig, and any \\$serviceAddress' in src/Admin/V2/Gapic/BigtableInstanceAdminGapicClient.php.
synthtool > Replaced '\\$transportConfig, and any \\$serviceAddress' in src/V2/Gapic/BigtableGapicClient.php.
synthtool > Replaced 'Copyright \\d{4}' in src/Admin/V2/Gapic/BigtableTableAdminGapicClient.php.
synthtool > Replaced 'Copyright \\d{4}' in src/Admin/V2/Gapic/BigtableInstanceAdminGapicClient.php.
synthtool > Replaced 'Copyright \\d{4}' in src/V2/Gapic/BigtableGapicClient.php.
synthtool > Replaced 'Copyright \\d{4}' in tests/Unit/V2/BigtableClientTest.php.
synthtool > Replaced 'Copyright \\d{4}' in tests/Unit/Admin/V2/BigtableInstanceAdminClientTest.php.
synthtool > Replaced 'Copyright \\d{4}' in tests/Unit/Admin/V2/BigtableTableAdminClientTest.php.
synthtool > Replaced 'namespace Google\\\\Cloud\\\\Bigtable\\\\Admin\\\\Tests\\\\Unit' in tests/Unit/Admin/V2/BigtableInstanceAdminClientTest.php.
synthtool > Replaced 'namespace Google\\\\Cloud\\\\Bigtable\\\\Admin\\\\Tests\\\\Unit' in tests/Unit/Admin/V2/BigtableTableAdminClientTest.php.
synthtool > Replaced '@group admin' in tests/Unit/Admin/V2/BigtableInstanceAdminClientTest.php.
synthtool > Replaced '@group admin' in tests/Unit/Admin/V2/BigtableTableAdminClientTest.php.
synthtool > Replaced 'new BigtableClient' in src/V2/Gapic/BigtableGapicClient.php.
synthtool > Replaced 'new BigtableInstanceAdminClient' in src/Admin/V2/Gapic/BigtableInstanceAdminGapicClient.php.
synthtool > Replaced '\\$instance = new Instance' in src/Admin/V2/Gapic/BigtableInstanceAdminGapicClient.php.
synthtool > Replaced '= Type::' in src/Admin/V2/Gapic/BigtableInstanceAdminGapicClient.php.
synthtool > Replaced 'new FieldMask' in src/Admin/V2/Gapic/BigtableInstanceAdminGapicClient.php.
synthtool > Replaced '\\$cluster = new Cluster' in src/Admin/V2/Gapic/BigtableInstanceAdminGapicClient.php.
synthtool > Replaced 'new AppProfile' in src/Admin/V2/Gapic/BigtableInstanceAdminGapicClient.php.
synthtool > Replaced 'new Policy' in src/Admin/V2/Gapic/BigtableTableAdminGapicClient.php.
synthtool > Replaced 'new Policy' in src/Admin/V2/Gapic/BigtableInstanceAdminGapicClient.php.
synthtool > Replaced 'new BigtableTableAdminClient' in src/Admin/V2/Gapic/BigtableTableAdminGapicClient.php.
synthtool > Replaced 'new Table' in src/Admin/V2/Gapic/BigtableTableAdminGapicClient.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/DeleteInstanceRequest.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/ModifyColumnFamiliesRequest.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/CreateTableFromSnapshotMetadata.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/ColumnFamily.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/DeleteClusterRequest.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/ListTablesRequest.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/SnapshotTableRequest.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/DropRowRangeRequest.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/ListTablesResponse.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/CreateInstanceMetadata.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/GetTableRequest.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/UpdateInstanceMetadata.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/CreateTableFromSnapshotRequest.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/Table.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/CheckConsistencyResponse.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/CreateInstanceRequest.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/UpdateClusterMetadata.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/GetClusterRequest.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/ListClustersResponse.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/CreateAppProfileRequest.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/CreateClusterRequest.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/PartialUpdateInstanceRequest.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/CreateTableRequest.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/ListAppProfilesRequest.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/ListSnapshotsResponse.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/GetInstanceRequest.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/ListInstancesRequest.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/Snapshot.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/SnapshotTableMetadata.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/DeleteAppProfileRequest.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/CreateClusterMetadata.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/Cluster.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/ListClustersRequest.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/GetAppProfileRequest.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/AppProfile.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/DeleteSnapshotRequest.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/UpdateAppProfileRequest.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/ListInstancesResponse.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/Instance.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/ListSnapshotsRequest.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/CheckConsistencyRequest.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/GenerateConsistencyTokenRequest.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/ListAppProfilesResponse.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/GetSnapshotRequest.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/DeleteTableRequest.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/GenerateConsistencyTokenResponse.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/AppProfile/SingleClusterRouting.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/CreateTableRequest/Split.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/ModifyColumnFamiliesRequest/Modification.php.
synthtool > Replaced 'Generated from protobuf field ([^\\n]{0,})\\n\\s{5}\\*/\\n\\s{4}protected \\$' in src/Admin/V2/Table/ClusterState.php.
synthtool > No replacements made in src/**/V*/**/*.php for pattern final class, maybe replacement is not longer needed?
synthtool > No replacements made in src/**/V*/**/*.php for pattern public function ([s|g]\w{3,})Unwrapped, maybe replacement is not longer needed?
synthtool > Wrote metadata to synth.metadata.