feat: add wechat QR code

close #354

Author: L1aoXingyu

.github/wechat_group.png

@@ -4,6 +4,11 @@
 
 Gitter: [fast-reid/community](https://gitter.im/fast-reid/community?utm_source=share-link&utm_medium=link&utm_campaign=share-link)
 
+Wechat: 
+
+<img src=".github/wechat_group.png" width="150" >
+
+
 FastReID is a research platform that implements state-of-the-art re-identification algorithms. It is a ground-up rewrite of the previous version, [reid strong baseline](https://github.com/michuanhaohao/reid-strong-baseline).
 
 ## What's New