Add sensors plugin to README of plugins (flutter#131)

README.md

@@ -26,6 +26,7 @@ These are the available plugins in this repository.
 | [package_info](./packages/package_info/) | [![pub package](https://img.shields.io/pub/v/package_info.svg)](https://pub.dartlang.org/packages/package_info) |
 | [path_provider](./packages/path_provider/) | [![pub package](https://img.shields.io/pub/v/path_provider.svg)](https://pub.dartlang.org/packages/path_provider) |
 | [quick_actions](./packages/quick_actions/) | [![pub package](https://img.shields.io/pub/v/quick_actions.svg)](https://pub.dartlang.org/packages/quick_actions) |
+| [sensors](./packages/sensors/) | [![pub package](https://img.shields.io/pub/v/sensors.svg)](https://pub.dartlang.org/packages/sensors) |
 | [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) |