Add a release notes for WildcardPatternSyntax.typeAnnotation

Author: rintaro

Release Notes/510.md

@@ -40,6 +40,10 @@
   - Issue: https://github.com/apple/swift-syntax/issues/2092
   - Pull Request: https://github.com/apple/swift-syntax/pull/2108
 
+- `WildcardPatternSyntax.typeAnnotation`
+  - Description: `typeAnnotation` on `WildcardPatternSyntax` was a mistake. Use `typeAnnotation` properties on the outer constructs instead. E.g. `PatternBindingListSyntax.typeAnnotation`
+  - Pull Request: https://github.com/apple/swift-syntax/pull/2393
+
 ## API-Incompatible Changes
 
 - `NoteMessage.fixItID` renamed to `noteID`