Add warning (#5770)

frontend/public/json/emqx.json

@@ -35,6 +35,10 @@
     {
       "text": "Setup-Steps: Access Control ➡ Authentication ➡ Create ➡ Next ➡ Next ➡ Create ➡ Users ➡ Add ➡ Username / Password (to authenicate with MQTT) ➡ Save. You're now ready to enjoy a high-performance MQTT Broker.",
       "type": "info"
+    },
+    {
+      "text": "WARNING: Installation sources scripts outside of Community Scripts repo. Please check the source before installing.",
+      "type": "warning"
     }
   ]
 }