Update dashboard.md

Author: gitplayer4

docs/user_manual/xpack/waf/dashboard.md

@@ -2,4 +2,4 @@
     On the Overview page, you can view today’s status, attack map, request trends, and block trends.
 
 ![img.png](../../../img/waf/dashboard.png){ width="900px" }
-{: .original}
+{: .browser-mockup}