Clarification on username and password for MQTT

config/config.yml

@@ -3,6 +3,8 @@ web_port: 5000
 mqtt:
   host: mqtt.server.com
   topic_prefix: frigate
+#  user: username # Optional -- Uncomment for use
+#  password: password # Optional -- Uncomment for use
 
 cameras:
   back: