docs/readme.md: Move Firestore "count" release notes entry to the correct version (#716)

Author: dconeybe

docs/readme.md

@@ -89,6 +89,9 @@ Release Notes
       deprecated methods will be removed in the *next* major release of the
       Firebase Unity SDK. *(Note: do not mix and match using the old
       and new methods or undefined behavior may result.)*
+    - Firestore: Added `Query.Count()`, which fetches the number of documents in
+      the result set without actually downloading the documents
+      ([#659](https://github.com/firebase/firebase-unity-sdk/pull/659)).
 
 ### 10.7.0
 - Changes
@@ -99,9 +102,6 @@ Release Notes
       as a Java file instead of precompiling it. This is to better support
       changes with the UnityPlayerActivity, and GameActivity options, in
       the Unity 2023 editor.
-    - Firestore: Added `Query.Count()`, which fetches the number of documents in
-      the result set without actually downloading the documents
-      ([#659](https://github.com/firebase/firebase-unity-sdk/pull/659)).
 
 ### 10.6.0
 - Changes