docs(router): Fix the link to the APP_BASE_HREF page

Author: Tragetaschen

public/docs/ts/latest/guide/router.jade

@@ -1612,7 +1612,7 @@ code-example(format=".", language="bash").
 
 .l-sub-section
   :marked
-    Learn about the [APP_BASE_HREF](../api/router/APP_BASE_HREF-let.html)
+    Learn about the [APP_BASE_HREF](../api/common/index/APP_BASE_HREF-let.html)
     in the API Guide.
 :marked
   ### *HashLocationStrategy*