docs, release notes

Signed-off-by: Andrew Mason <[email protected]>

changelog/17.0/17.0.0/summary.md

@@ -5,6 +5,7 @@
 - **[Major Changes](#major-changes)**
   - **[Breaking Changes](#breaking-changes)**
     - [Dedicated stats for VTGate Prepare operations](#dedicated-vtgate-prepare-stats)
+    - [Keyspace name validation in TopoServer](#keyspace-name-validation)
   - **[New command line flags and behavior](#new-flag)**
     - [Builtin backup: read buffering flags](#builtin-backup-read-buffering-flags)
   - **[New stats](#new-stats)**
@@ -49,6 +50,16 @@ Here is a (condensed) example of stats output:
 }
 ```
 
+
+#### <a id="keyspace-name-validation"> Keyspace name validation in TopoServer
+
+Prior to v17, it was possible to create a keyspace with invalid characters, which would then be inaccessible to various cluster management operations.
+
+Now, the TopoServer's `GetKeyspace` and `CreateKeyspace` methods return an error if given an invalid name.
+
+Keyspace names may no longer contain the following characters:
+- Forward slash ("/").
+
 ### <a id="new-flag"/> New command line flags and behavior
 
 #### <a id="builtin-backup-read-buffering-flags" /> Backup --builtinbackup-file-read-buffer-size and --builtinbackup-file-write-buffer-size

go/vt/topo/keyspace.go

@@ -56,6 +56,14 @@ func (ki *KeyspaceInfo) SetKeyspaceName(name string) {
 
 var ksNameReplacer = strings.NewReplacer("/", "")
 
+// ValidateKeyspaceNames checks if the provided name is a valid name for a
+// keyspace.
+//
+// If it is valid, the original name is returned with no error. If it is
+// invalid, the name with all invalid characters removed is returned, along
+// with an error.
+//
+// As of v17, "all invalid characters" is just the forward slash ("/").
 func ValidateKeyspaceName(name string) (string, error) {
 	if validated := ksNameReplacer.Replace(name); name != validated {
 		return validated, vterrors.Errorf(vtrpcpb.Code_INVALID_ARGUMENT, "keyspace name %s contains invalid characters; expected %s instead", name, validated)