doc: Update README.md

Author: jaywcjlove

README.md

@@ -1,5 +1,9 @@
-@uiw/react-native-wechat
------
+<p align="center">
+  <a href="https://uiwjs.github.io/react-native-wechat/">
+    <img src="https://user-images.githubusercontent.com/1680273/89100258-46cf6a00-d428-11ea-96dc-8b07a0ee277c.png" height="100" />
+  </a>
+  <h1 align="center">@uiw/react-native-wechat</h1>
+<p>
 
 [![NPM Version](https://img.shields.io/npm/v/@uiw/react-native-wechat.svg)](https://npmjs.org/package/@uiw/react-native-wechat)