docs: Update documentation.

[yoshi-automation]

This PR was generated using Autosynth. 🌈

Here's the log from Synthtool:

synthtool > Executing /tmpfs/src/git/autosynth/working_repo/WebRisk/synth.py.
synthtool > Ensuring dependencies.
synthtool > Pulling artman image.
latest: Pulling from googleapis/artman
Digest: sha256:0d2f8d429110aeb8d82df6550ef4ede59d40df9062d260a1580fce688b0512bf
Status: Image is up to date for googleapis/artman:latest
synthtool > Cloning googleapis.
synthtool > Running generator for google/cloud/webrisk/artman_webrisk_v1beta1.yaml.
synthtool > Generated code into /home/kbuilder/.cache/synthtool/googleapis/artman-genfiles/php/google-cloud-webrisk-v1beta1.
synthtool > No files in sources /home/kbuilder/.cache/synthtool/googleapis/artman-genfiles/php/google-cloud-webrisk-v1beta1/proto/src/GPBMetadata/Google/Cloud/WebRisk were copied. Does the source contain files?
synthtool > Replaced "'serviceAddress' =>" in src/V1beta1/Gapic/WebRiskServiceV1Beta1GapicClient.php.
synthtool > Replaced '@type string \\$serviceAddress\\n\\s+\\*\\s+The address' in src/V1beta1/Gapic/WebRiskServiceV1Beta1GapicClient.php.
synthtool > Replaced '\\$transportConfig, and any \\$serviceAddress' in src/V1beta1/Gapic/WebRiskServiceV1Beta1GapicClient.php.
synthtool > Replaced 'final class' in src/V1beta1/SearchHashesResponse.php.
synthtool > Replaced 'final class' in src/V1beta1/RiceDeltaEncoding.php.
synthtool > Replaced 'final class' in src/V1beta1/ThreatEntryAdditions.php.
synthtool > Replaced 'final class' in src/V1beta1/SearchUrisRequest.php.
synthtool > Replaced 'final class' in src/V1beta1/ComputeThreatListDiffResponse.php.
synthtool > Replaced 'final class' in src/V1beta1/ThreatEntryRemovals.php.
synthtool > Replaced 'final class' in src/V1beta1/ComputeThreatListDiffRequest.php.
synthtool > Replaced 'final class' in src/V1beta1/SearchUrisResponse.php.
synthtool > Replaced 'final class' in src/V1beta1/SearchHashesRequest.php.
synthtool > Replaced 'final class' in src/V1beta1/RawHashes.php.
synthtool > Replaced 'final class' in src/V1beta1/RawIndices.php.
synthtool > Replaced 'final class' in src/V1beta1/SearchUrisResponse/ThreatUri.php.
synthtool > Replaced 'final class' in src/V1beta1/ComputeThreatListDiffResponse/Checksum.php.
synthtool > Replaced 'final class' in src/V1beta1/SearchHashesResponse/ThreatHash.php.
synthtool > Replaced 'final class' in src/V1beta1/ComputeThreatListDiffRequest/Constraints.php.
synthtool > No replacements made in src/V*/**/*.php for pattern public function ([s|g]\w{3,})Unwrapped, maybe replacement is not longer needed?
synthtool > Replaced 'Copyright \\d{4}' in src/V1beta1/Gapic/WebRiskServiceV1Beta1GapicClient.php.
synthtool > Replaced 'Copyright \\d{4}' in tests/Unit/V1beta1/WebRiskServiceV1Beta1ClientTest.php.
synthtool > Replaced 'new Constraints' in src/V1beta1/Gapic/WebRiskServiceV1Beta1GapicClient.php.
synthtool > Replaced '= ThreatType::' in src/V1beta1/Gapic/WebRiskServiceV1Beta1GapicClient.php.
synthtool > Replaced '= new WebRiskServiceV1Beta1Client' in src/V1beta1/Gapic/WebRiskServiceV1Beta1GapicClient.php.
synthtool > Cleaned up 1 temporary directories.
synthtool > Wrote metadata to synth.metadata.

[codecov]

Codecov Report

Merging #2389 into master will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master    #2389   +/-   ##
=========================================
  Coverage     92.55%   92.55%           
  Complexity     4503     4503           
=========================================
  Files           312      312           
  Lines         13497    13497           
=========================================
  Hits          12492    12492           
  Misses         1005     1005

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