add apollo portal demo with public server.

README.md

@@ -22,6 +22,10 @@ Java客户端不依赖任何框架，能够运行于所有Java运行时环境，
 
 本地快速部署请参见[Quick Start](https://github.com/ctripcorp/apollo/wiki/Quick-Start)
 
+公益演示环境（Demo）:
+- [140.143.100.23:8070](http://140.143.100.23:8070/)
+- 账号/密码:apollo/admin
+
 # Screenshots
 ![配置界面](https://raw.githubusercontent.com/ctripcorp/apollo/master/doc/images/apollo-home-screenshot.png)