Use up -d instead of start when creating first time.

README.md

@@ -81,7 +81,7 @@ $ mkdir -p /opt/mailman/web
 $ git clone https://github.com/maxking/docker-mailman
 $ cd docker-mailman
 # Change some configuration variables as mentioned above.
-$ docker-compose start
+$ docker-compose up -d
 ```
 
 This command will do several things, most importantly: