Update waf.md

Author: gitplayer4

docs/user_manual/xpack/waf/waf.md

@@ -3,4 +3,4 @@
     It protects your website against malicious attacks such as SQL injection and XSS.
 
 ![img.png](../../../img/waf/dashboard.png){ width="900px" }
-{: .original}
+{: .browser-mockup}