Update README.md

Author: dawning7670

README.md

@@ -11,7 +11,7 @@ go build
 
 ### Usage
 
-Start volume plugin
+##### Start volume plugin
 
 - `server` :  glusterfs nodes. 
 - `etcd` : etcd server address. when plugin running in multi-host environment, it must required, because plugin use etcd to sync docker volume config between hosts
@@ -20,13 +20,15 @@ Start volume plugin
 docker-gluster-volume-plugin -server server1:server2:server3 -etcd http://<ip>:<port>
 ```
 
-Create volume, the `vname`is your gluster volume name
+##### Create volume
 
-```
+- `vname`is your gluster volume name
+
+```sh
 docker volume create --driver glusterfs --opt vname="gv5" --name d-gv5
 ```
 
-Run container
+##### Run container
 
 ```sh
 docker run --name test -v d-gv5:/data -td ubuntu:14.04.3