Added pub and separated FlutterFire plugins (firebase#92)

Another iteration. One of these can be closed. 

This is using the table with a division to separate the FlutterFire plugins.

README.md

@@ -19,17 +19,21 @@ These are the available plugins in this repository.
 | Plugin | Pub |
 |--------|-----|
 | [battery](./packages/battery/) | [![pub package](https://img.shields.io/pub/v/battery.svg)](https://pub.dartlang.org/packages/battery) |
-| [firebase_analytics](./packages/firebase_analytics/) | [![pub package](https://img.shields.io/pub/v/firebase_analytics.svg)](https://pub.dartlang.org/packages/firebase_analytics) |
-| [firebase_auth](./packages/firebase_auth/) | [![pub package](https://img.shields.io/pub/v/firebase_auth.svg)](https://pub.dartlang.org/packages/firebase_auth) |
-| [firebase_database](./packages/firebase_database/) | [![pub package](https://img.shields.io/pub/v/firebase_database.svg)](https://pub.dartlang.org/packages/firebase_database) |
-| [firebase_messaging](./packages/firebase_messaging/) | [![pub package](https://img.shields.io/pub/v/firebase_messaging.svg)](https://pub.dartlang.org/packages/firebase_messaging) |
-| [firebase_storage](./packages/firebase_storage/) | [![pub package](https://img.shields.io/pub/v/firebase_storage.svg)](https://pub.dartlang.org/packages/firebase_storage) |
 | [google_sign_in](./packages/google_sign_in/) | [![pub package](https://img.shields.io/pub/v/google_sign_in.svg)](https://pub.dartlang.org/packages/google_sign_in) |
 | [image_picker](./packages/image_picker/) | [![pub package](https://img.shields.io/pub/v/image_picker.svg)](https://pub.dartlang.org/packages/image_picker) |
 | [path_provider](./packages/path_provider/) | [![pub package](https://img.shields.io/pub/v/path_provider.svg)](https://pub.dartlang.org/packages/path_provider) |
 | [share](./packages/share/) | [![pub package](https://img.shields.io/pub/v/share.svg)](https://pub.dartlang.org/packages/share) |
 | [shared_preferences](./packages/shared_preferences/) | [![pub package](https://img.shields.io/pub/v/shared_preferences.svg)](https://pub.dartlang.org/packages/shared_preferences) |
 | [url_launcher](./packages/url_launcher/) | [![pub package](https://img.shields.io/pub/v/url_launcher.svg)](https://pub.dartlang.org/packages/url_launcher) |
+| | |
+| **FlutterFire Plugins** |  |
+| [firebase_analytics](./packages/firebase_analytics/) | [![pub package](https://img.shields.io/pub/v/firebase_analytics.svg)](https://pub.dartlang.org/packages/firebase_analytics) |
+| [firebase_auth](./packages/firebase_auth/) | [![pub package](https://img.shields.io/pub/v/firebase_auth.svg)](https://pub.dartlang.org/packages/firebase_auth) |
+| [firebase_database](./packages/firebase_database/) | [![pub package](https://img.shields.io/pub/v/firebase_database.svg)](https://pub.dartlang.org/packages/firebase_database) |
+| [firebase_messaging](./packages/firebase_messaging/) | [![pub package](https://img.shields.io/pub/v/firebase_messaging.svg)](https://pub.dartlang.org/packages/firebase_messaging) |
+| [firebase_storage](./packages/firebase_storage/) | [![pub package](https://img.shields.io/pub/v/firebase_storage.svg)](https://pub.dartlang.org/packages/firebase_storage) |
+
+Learn more about [FlutterFire](https://github.com/flutter/plugins/blob/master/FlutterFire.md).
 
 ## Issues