Updated Readme file

Author: karthiks

.idea/markdown-navigator.xml

@@ -9,3 +9,6 @@ Android Authentication with Firebase using Google Auth
 * [Firebase - docs - Android - Getting Started](https://firebase.google.com/docs/auth/android/start/)
 * [Personalize your Android App with Firebase User Management](https://codelabs.developers.google.com/codelabs/firebase-auth-android/index.html?index=..%2F..%2Findex#0)
 * [Video] [Android Studio Tutorial - Google Sign In - Firebase Authentication - Part 16](https://www.youtube.com/watch?v=-ywVw2O1pP8)
+
+## Alternative Implementation
+* I think it is much easier to use [FirebaseUI for Android](https://github.com/firebase/FirebaseUI-Android/blob/master/auth/README.md) for quick implementaion of various auth mechanisms.