provide actual command format for docker network create

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

docs/reference/commandline/network_create.md

@@ -11,7 +11,7 @@ parent = "smn_cli"
 # network create
 
 ```markdown
-Usage:	docker network create [OPTIONS]
+Usage:	docker network create [OPTIONS] NETWORK
 
 Create a network