fix wrong output titile for docker volume ls

Signed-off-by: lixiaobing10051267 <li.xiaobing1@zte.com.cn>

docs/extend/index.md

@@ -97,7 +97,7 @@ started without error.
     ```bash
     $ docker volume ls
 
-    DRIVER              NAME
+    DRIVER              VOLUME NAME
     vieux/sshfs         sshvolume
     ```
 

docs/reference/commandline/volume_ls.md

@@ -99,7 +99,7 @@ regardless of its value.
 ```bash
 $ docker volume ls --filter label=is-timelord
 
-DRIVER              NAME
+DRIVER              VOLUME NAME
 local               daleks
 local               the-doctor
 ```
@@ -112,7 +112,7 @@ Filtering on both `key` *and* `value` of the label, produces the expected result
 ```bash
 $ docker volume ls --filter label=is-timelord=yes
 
-DRIVER              NAME
+DRIVER              VOLUME NAME
 local               the-doctor
 ```
 
@@ -122,7 +122,7 @@ should be met;
 ```bash
 $ docker volume ls --filter label=is-timelord=yes --filter label=is-timelord=no
 
-DRIVER              NAME
+DRIVER              VOLUME NAME
 ```
 
 ### name