Add release note for Trivia.commentValue

Author: zyadtaha

Release Notes/602.md

@@ -2,6 +2,10 @@
 
 ## New APIs
 
+- `Trivia` has a new `commentValue` property.
+  - Description: Extracts sanitized comment text from comment trivia pieces, omitting leading comment markers (`//`, `///`, `/*`, `*/`).
+  - Pull Request: https://github.com/swiftlang/swift-syntax/pull/2966
+
 ## API Behavior Changes
 
 ## Deprecations