Merge pull request #5321 from mysterywolf/readme

update readme

README.md

-# RT-Thread #
+<p align="center">
+<img src="documentation/figures/logo.png" width="60%" >
+</p>
 
 **English** | [中文](README_zh.md) |
 
@@ -9,7 +11,7 @@
 [![GitHub pull-requests](https://img.shields.io/github/issues-pr/RT-Thread/rt-thread.svg)](https://github.com/RT-Thread/rt-thread/pulls)
 [![PRs Welcome](https://img.shields.io/badge/PRs-welcome-brightgreen.svg?style=flat)](https://github.com/RT-Thread/rt-thread/pulls)
 
-# Introduction
+# RT-Thread
 
 RT-Thread was born in 2006, it is an open source, neutral, and community-based real-time operating system (RTOS).
 

README_zh.md

@@ -169,7 +169,7 @@ RT-Thread非常感谢所有社区小伙伴的支持，在使用RT-Thread的过
 
 RT-Thread微信公众号：
 
-![qrcode](./documentation/figures/qrcode.png)
+![qrcode](./documentation/figures/qrcode.jpg)
 
 
 # 贡献代码