Added `network` to docker --help and help cleanup

Fixes https://github.com/docker/docker/issues/16909

Signed-off-by: Madhu Venugopal <madhu@docker.com>

common.go

@@ -45,6 +45,7 @@ var dockerCommands = []Command{
 	{"login", "Register or log in to a Docker registry"},
 	{"logout", "Log out from a Docker registry"},
 	{"logs", "Fetch the logs of a container"},
+	{"network", "Manage Docker networks"},
 	{"pause", "Pause all processes within a container"},
 	{"port", "List port mappings or a specific mapping for the CONTAINER"},
 	{"ps", "List containers"},