set master ip

Getting-Started.md

@@ -75,7 +75,7 @@ Now you can use your tools to hit SeaweedFS as hard as you can.
 Use with docker is easy as run locally, you can pass all args like above. But you don't need to worry about "-ip". It'll be treated by the entrypoint script.
 
 ```
-docker run -p 9333:9333 --name master chrislusf/seaweedfs master
+docker run -p 9333:9333 --name master chrislusf/seaweedfs master -ip=master
 ```
 ```
 docker run -p 8080:8080 -p 18080:18080 --name volume --link master chrislusf/seaweedfs volume -max=5 -mserver="master:9333" -port=8080