Update release notes comparison link

CHANGELOG.md

@@ -305,7 +305,7 @@ For more information, please see the [`useResolvedPath` docs](https://reactroute
 - Catch and bubble errors thrown when trying to unwrap responses from `loader`/`action` functions ([#11061](https://github.com/remix-run/react-router/pull/11061))
 - Fix `relative="path"` issue when rendering `Link`/`NavLink` outside of matched routes ([#11062](https://github.com/remix-run/react-router/pull/11062))
 
-**Full Changelog**: [`v6.X.Y...v6.X.Y`](https://github.com/remix-run/react-router/compare/react-router@6.X.Y...react-router@6.X.Y)
+**Full Changelog**: [`v6.20.1...v6.21.0`](https://github.com/remix-run/react-router/compare/react-router@6.20.1...react-router@6.21.0)
 
 ## v6.20.1