Restore unreleased link and add v16.2.0.beta.13 link

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: justin808

CHANGELOG.md

@@ -1856,6 +1856,7 @@ such as:
 
 - Fix several generator-related issues.
 
+[unreleased]: https://github.com/shakacode/react_on_rails/compare/v16.2.0.beta.13...master
 [v16.2.0.beta.13]: https://github.com/shakacode/react_on_rails/compare/v16.2.0.beta.11...v16.2.0.beta.13
 [v16.2.0.beta.11]: https://github.com/shakacode/react_on_rails/compare/16.1.1...v16.2.0.beta.11
 [16.1.1]: https://github.com/shakacode/react_on_rails/compare/16.1.0...16.1.1