Update README
Update README

Change-Id: Ia2aa819141ee577ba61601c84bb33148eb16004e

SUPERCILEX/FirebaseUI-Android,samtstern/FirebaseUI-Android,firebase/FirebaseUI-Android,firebase/FirebaseUI-Android,samtstern/FirebaseUI-Android,SUPERCILEX/FirebaseUI-Android,JosefHruska/FirebaseUI-Android,firebase/FirebaseUI-Android,SUPERCILEX/FirebaseUI-Android,JosefHruska/FirebaseUI-Android,SUPERCILEX/FirebaseUI-Android,MaciejCiemiega/FirebaseUI-Android,firebase/FirebaseUI-Android,samtstern/FirebaseUI-Android