Update CHANGELOG.md

Author: ncooke3

FirebaseAuth/CHANGELOG.md

@@ -5,11 +5,13 @@
   `Auth.currentUser` API. This resolves some Firebase 11 issues where the
   current user is unexpectedly `nil` at startup.
 - [fixed] Restore Firebase 10 decoding behavior to prevent user provider data
-  from always being decoded as `nil` when reading Firebase 10 data. (#14011)
+  from always being decoded as `nil` . Note that this fix was only needed for
+  cases Firebase 11 was reading data written by Firebase 10. (#14011)
 - [fixed] Restore Firebase 10 decoding behavior to prevent user provider data
   from being decoded as `nil` when a user has multiple linked providers. Note
-  that this fix will not be in the 11.6.0 zip and Carthage distributions, but
-  will be included from 11.6.0 onwards. (#14011)
+  that this fix was only needed for cases Firebase 11 was reading data written
+  by Firebase 10. Note that this fix will not be in the 11.6.0 zip and
+  Carthage distributions, but will be included from 11.6.0 onwards. (#14011)
 
 # 11.5.0
 - [fixed] Restore pre-Firebase 11 decoding behavior to prevent users getting