English README: fix online testing url

TommyLemon · web-flow · commit a9efd6ddcfd1 · 2021-06-07T00:17:53.000+08:00
diff --git a/README-English.md b/README-English.md
@@ -160,7 +160,7 @@ Response:
 
 <br />
 
-[Test it online](http://apijson.cn/)<br />
+[Test it online](http://apijson.cn/api)<br />
 
 ![](https://raw.githubusercontent.com/TommyLemon/StaticResources/master/APIJSON_Auto_get.jpg) 
 
