Merge pull request #879 from danibonilha/patch-1

Update documentation to avoid falling Androids' build

Author: Gp2mv3

README.md

@@ -38,7 +38,7 @@ The component uses PushNotificationIOS for the iOS part.
 
 ## Android manual Installation
 
-**NOTE: To use a specific `play-service-gcm` or `firebase-messaging` version:**
+**NOTE: `play-service-gcm` and `firebase-messaging`, prior to version 15 requires to have the same version number in order to work correctly at build time and at run time. To use a specific version:**
 
 In your `android/build.gradle`
 ```gradle