Update Overview for SRS

README.md

@@ -17,7 +17,7 @@ SRS/4.0，[Leo][release4]，是一个简单高效的实时视频服务器，支
 
 SRS is a simple, high efficiency and realtime video server, supports RTMP/WebRTC/HLS/HTTP-FLV/SRT.
 
-[![SRS Overview](https://gitee.com/winlinvip/srs-wiki/raw/master/images/SRS-Overview.png)](https://gitee.com/winlinvip/srs-wiki/raw/master/images/SRS-Overview.png)
+[![SRS Overview](https://gitee.com/winlinvip/srs-wiki/raw/master/images/SRS-Overview-4.0.png)](https://gitee.com/winlinvip/srs-wiki/raw/master/images/SRS-Overview-4.0.png)
 
 > Note: Please see https://www.processon.com/view/link/619f29791efad425fd699fd2