update doc

README.md

@@ -44,6 +44,7 @@ void getHttp() async {
 | [dio_http2_adapter](https://github.com/flutterchina/dio/tree/master/plugins/http2_adapter) | [![Pub](https://img.shields.io/pub/v/dio_cookie_manager.svg?style=flat-square)](https://pub.dartlang.org/packages/dio_cookie_manager) | A Dio HttpClientAdapter which support Http/2.0               |
 | [dio_flutter_transformer](https://github.com/flutterchina/dio_flutter_transformer) | [![Pub](https://img.shields.io/pub/v/dio_flutter_transformer.svg?style=flat-square)](https://pub.dartlang.org/packages/dio_flutter_transformer) | A Dio transformer especially for flutter, by which the json decoding will be in background with `compute` function. |
 | [dio_http_cache](https://github.com/hurshi/dio-http-cache)   | [![Pub](https://img.shields.io/pub/v/dio_http_cache.svg?style=flat-square)](https://pub.dartlang.org/packages/dio_http_cache) | A cache library for Dio, like [Rxcache](https://github.com/VictorAlbertos/RxCache) in Android. dio-http-cache uses [sqflite](https://github.com/tekartik/sqflite) as disk cache, and [LRU](https://github.com/google/quiver-dart) strategy as memory cache. |
+| [retrofit](https://github.com/trevorwang/retrofit.dart/)     | [![Pub](https://img.shields.io/pub/v/retrofit.svg?style=flat-square)](https://pub.dartlang.org/packages/retrofit) | retrofit.dart is an dio client generator using source_gen and inspired by Chopper and Retrofit. |
 
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