Update Release Notes for v10.2.0 (#553)

pdate the release notes for the upcoming v10.2.0 release.
Release notes reflect the update in the iOS and Android dependencies.

Author: DellaBitta

docs/readme.md

@@ -67,6 +67,11 @@ Support
 
 Release Notes
 -------------
+### 10.2.0
+- Changes
+    - General (Android): Update to Firebase Android BoM version 31.1.0.
+    - General (iOS): Update to Firebase Cocoapods version 10.2.0.
+
 ### 10.1.1
 - Changes
     - General (Android): Update to Firebase Android BoM version 31.0.3.