Update readme.

Author: jonsimantov

release_build_files/readme.md

@@ -656,6 +656,7 @@ code.
 ## Release Notes
 ### 12.8.0
 -   Changes
+    - General (iOS): Update to Firebase Cocoapods version 11.13.0.
     - General (iOS, tvOS, Desktop): iOS, tvOS, and macOS SDKs are now built
       using Xcode 16.2.
     - UMP: Moved the User Messaging Platform SDK to its own top-level