Update README

Author: gryamy

README.md

@@ -1,7 +1,7 @@
 ![Matrix-icon](assets/img/readme/header.png)
 [![license](http://img.shields.io/badge/license-BSD3-brightgreen.svg?style=flat)](https://github.com/Tencent/matrix/blob/master/LICENSE)
 [![PRs Welcome](https://img.shields.io/badge/PRs-welcome-brightgreen.svg)](https://github.com/Tencent/matrix/pulls)
-[![WeChat Approved](https://img.shields.io/badge/Wechat%20Approved-2.0.0.beta-red.svg)](https://github.com/Tencent/matrix/wiki)
+[![WeChat Approved](https://img.shields.io/badge/Wechat%20Approved-2.0.0-red.svg)](https://github.com/Tencent/matrix/wiki)
 [![CircleCI](https://circleci.com/gh/Tencent/matrix.svg?style=shield)](https://app.circleci.com/pipelines/github/Tencent/matrix)
 
 (中文版本请参看[这里](#matrix_cn))