docs: README add community (#1922)

Signed-off-by: wxuanF <2569456943@qq.com>

README.md

@@ -161,6 +161,8 @@ Before you start, please make sure your changes are in demand. The best for that
 + 💕 [OpenIM Interest Group](https://github.com/Openim-sigs)
 + 🚀 [Join our Slack community](https://join.slack.com/t/openimsdk/shared_invite/zt-22720d66b-o_FvKxMTGXtcnnnHiMqe9Q)
 + :eyes: [Join our wechat (微信群)](https://openim-1253691595.cos.ap-nanjing.myqcloud.com/WechatIMG20.jpeg)
++ 👫 [Join our Reddit](https://www.reddit.com/r/OpenIMessaging)
++ 💬 [Follow our Twitter account](https://twitter.com/openimsdk)
 
 ## :calendar: Community Meetings