Add camera plugin to readme (firebase#618)

README.md

@@ -42,6 +42,7 @@ These are the available plugins in this repository.
 | [android_alarm_manager](./packages/android_alarm_manager/) | [![pub package](https://img.shields.io/pub/v/android_alarm_manager.svg)](https://pub.dartlang.org/packages/android_alarm_manager) |
 | [android_intent](./packages/android_intent/) | [![pub package](https://img.shields.io/pub/v/android_intent.svg)](https://pub.dartlang.org/packages/android_intent) |
 | [battery](./packages/battery/) | [![pub package](https://img.shields.io/pub/v/battery.svg)](https://pub.dartlang.org/packages/battery) |
+| [camera](./packages/camera/) | [![pub package](https://img.shields.io/pub/v/camera.svg)](https://pub.dartlang.org/packages/camera) |
 | [connectivity](./packages/connectivity/) | [![pub package](https://img.shields.io/pub/v/connectivity.svg)](https://pub.dartlang.org/packages/connectivity) |
 | [device info](./packages/device_info/) | [![pub package](https://img.shields.io/pub/v/device_info.svg)](https://pub.dartlang.org/packages/device_info) |
 | [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) |