FirebaseMessaging changelog: FirebaseInstallations (#4625)

* FirebaseMessaging changelog: FirebaseInstallations

* FirebaseInstallations changelog: header format consistent with FirebaseCore

* dependency -> transitive dependency

* corrections

Author: maksymmalyhin

Firebase/Messaging/CHANGELOG.md

@@ -1,5 +1,6 @@
 # 2020-01 -- v 4.2.0
 - [added] Added watchOS support for Firebase Messaging. This enables FCM push notification function on watch only app or independent watch app. (#4016)
+- [added] Added a new transitive dependency [Firebase Installations SDK](../../FirebaseInstallations/CHANGELOG.md). The Firebase Installations SDK introduces the [Firebase Installations API](https://pantheon.corp.google.com/apis/library/firebaseinstallations.googleapis.com). Developers that use API-restrictions for their API-Keys may experience blocked requests (https://stackoverflow.com/questions/58495985/). A solution is available [here](../../FirebaseInstallations/API_KEY_RESTRICTIONS.md).
 
 # 2019-12 -- v4.1.10
 - [fixed] Fix component startup time. (#4137)

FirebaseInstallations/CHANGELOG.md

@@ -1,4 +1,4 @@
-# 1.0.0
+# v1.0.0 -- M62
 
 - [added] The Firebase Installations Service is an infrastructure service for Firebase services that creates unique identifiers and authentication tokens for Firebase clients (called "Firebase Installations") enabling Firebase Targeting, i.e. interoperation between Firebase services.
 - [added] The Firebase Installations SDK introduces the Firebase Installations API. Developers that use API-restrictions for their API-Key may experience blocked requests (https://stackoverflow.com/questions/58495985/). This problem can be mitigated by following the instructions found [here](API_KEY_RESTRICTIONS.md).