Add release note for this fix.

Author: jonsimantov

release_build_files/readme.md

@@ -567,6 +567,11 @@ workflow use only during the development of your app, not for publicly shipping
 code.
 
 ## Release Notes
+### Upcoming Release
+-   Changes
+    -   General (iOS): Fixed additional issues on iOS 15 caused by early
+        initialization of Firebase iOS SDK.
+
 ### 8.9.0
 -   Changes
     -   General (iOS): Fixed an intermittent crash on iOS 15 caused by