Update mosquitto.markdown

source/_addons/mosquitto.markdown

@@ -18,7 +18,11 @@ Set up a [mosquitto](https://mosquitto.org/) MQTT broker.
   "anonymous": true,
   "logins": [
     {"username": "testuser", "password": "mypw"}
-  ]
+  ],
+  "customize": {
+    "active": false,
+    "folder": "mosquitto
+  }
 }
 ```
 
@@ -30,6 +34,7 @@ Configuration variables:
 - **ssl** (*Optional*): Listen to broker on port 8883 with SSL/TLS. This requires certificates. Defaults to `false`.
 - **anonymous** (*Optional*): Allow anonymous connection. If *logins* is set, anonymous user can only read data. Defaults to `true`.
 - **logins** (*Optional*): A list of user that will be created with *username* and *password*.
+- **customize** (*Optional*): If you enable it, it read additional config files (`*.conf`) from `/share/mosquitto`.
 
 ### {% linkable_title Home Assistant configuration %}