update readme, add csdn mirror

 #Simple-RTMP-Server
 
-[下载发布版(github): Download Released SRS from github](http://winlinvip.github.io/srs.release/releases/)
+下载发布版(github): [Centos6-x86_64](http://winlinvip.github.io/srs.release/releases/files/SRS-CentOS6-x86_64-0.9.30.zip) [alternative downloads](http://winlinvip.github.io/srs.release/releases/)
 
-[下载发布版(国内阿里云镜像): Download Realeased SRS from chnvideo mirror](http://demo.chnvideo.com:8085/srs/releases/)
+下载发布版(国内阿里云镜像): [Centos6-x86_64](http://demo.chnvideo.com:8085/srs/releases/files/SRS-CentOS6-x86_64-0.9.30.zip) [alternative downloads](http://demo.chnvideo.com:8085/srs/releases/)
 
-[获得源码(github): Checkout SRS source from github](https://github.com/winlinvip/simple-rtmp-server)
+获得源码(github): [simple-rtmp-server](https://github.com/winlinvip/simple-rtmp-server)
 
 ```bash
 git clone https://github.com/winlinvip/simple-rtmp-server.git
 ```
 
-[获得源码(国内CSDN镜像): Checkout SRS source from CSDN](https://code.csdn.net/winlinvip/srs-csdn/events)
+获得源码(国内CSDN镜像): [simple-rtmp-server](https://code.csdn.net/winlinvip/srs-csdn/events)
 
 ```bash
 git clone https://code.csdn.net/winlinvip/srs-csdn.git