Normalize the log for docker subcommand usage,

delete unecessary blank after "[OPTIONS] "
and add a blank to the log between options and signature.

To make the code style consistency.

Signed-off-by: Zen Lin(Zhinan Lin) <linzhinan@huawei.com>

integration-cli/docker_cli_help_test.go

@@ -130,7 +130,7 @@ func TestHelpTextVerify(t *testing.T) {
 				if strings.HasPrefix(line, "  -") && strings.HasSuffix(line, ".") {
 					t.Fatalf("Help for %q should not end with a period: %s", cmd, line)
 				}
-				
+
 				// Options should not end with a space
 				if strings.HasSuffix(line, " ") {
 					t.Fatalf("Help for %q should not end with a space: %s", cmd, line)