Update README.md

Author: andrehtissot

README.md

@@ -47,10 +47,11 @@ Make sure you have ‘google-services.json’ for Android or ‘GoogleService-In
 
 |Preference|Default Value|Description|
 |---|---|---|
-|ANDROID_FCM_VERSION|19.0.0|Android's native Firebase Message SDK version.|
-|ANDROID_GRADLE_TOOLS_VERSION|3.5.3|Android's Gradle tools version.|
-|ANDROID_GOOGLE_SERVICES_VERSION|4.3.3|Android's native Google Services SDK version.|
-|ANDROID_DEFAULT_NOTIFICATION_ICON|@mipmap/ic_launcher|Android's default notification icon.|
+|ANDROID_DEFAULT_NOTIFICATION_ICON|@mipmap/ic_launcher|Default notification icon.|
+|ANDROID_FCM_VERSION|21.0.0|Native Firebase Message SDK version :warning: Replaced by BoM versioning on Gradle >= 3.4.|
+|ANDROID_FIREBASE_BOM_VERSION|26.0.0|[Firebase BoM](https://firebase.google.com/docs/android/learn-more#bom) version.|
+|ANDROID_GOOGLE_SERVICES_VERSION|4.3.4|Native Google Services SDK version.|
+|ANDROID_GRADLE_TOOLS_VERSION|4.1.0|Gradle tools version.|
 
 #### Cordova