Specify woker node for docker swarm leave command

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

docs/reference/commandline/swarm_leave.md

@@ -31,7 +31,7 @@ dkp8vy1dq1kxleu9g4u78tlag    worker1   Ready   Active        Reachable
 dvfxp4zseq4s0rih1selh0d20 *  manager1  Ready   Active        Leader
 ```
 
-On a worker node:
+On a worker node, worker2 in the following example:
 ```bash
 $ docker swarm leave
 Node left the default swarm.