Add Release notes

Author: dellis1972

Documentation/release-notes/5186.md renamed to Documentation/release-notes/5304.md

@@ -1,6 +1,6 @@
 ### Build and deployment performance
 
-  * [GitHub PR 5186](https://github.com/xamarin/xamarin-android/pull/5186):
+  * [GitHub PR 5304](https://github.com/xamarin/xamarin-android/pull/5304):
     Add support for producing a proguard `mapping.txt` file to the
     build system. This file can be used by users to remove this warning