Add mqtt config example

mosquitto/config/mosquitto.conf.example

@@ -0,0 +1,14 @@
+persistence true
+persistence_location /mosquitto/data/
+
+log_dest stdout
+log_dest file /mosquitto/log/mosquitto.log
+log_type warning
+log_timestamp true
+connection_messages true
+
+listener 1883
+
+## Authentication ##
+#allow_anonymous false
+#password_file /mosquitto/config/password.txt