update demo url

Li Shuai · Li Shuai · commit 959b899a6fec · 2021-02-05T18:33:19.000+08:00
diff --git a/docs/README.md b/docs/README.md
@@ -22,7 +22,7 @@
 zh-cn: **https://www.yuque.com/httpreports/docs**  
 en-us: **https://www.yuque.com/httpreports/docs?language=en-us**
 
-**The online preview**： **http://122.51.188.23:8080**   
+**The online preview**： **http://apm.nonop.cn/**   
 
 account: **admin** password **123456 **  
 
