fix incorrect argc < 1 check for no arguments

-requiring arguments should be argc < 2

src/modules/commander/commander.cpp

@@ -261,7 +261,7 @@ void answer_command(struct vehicle_command_s &cmd, enum VEHICLE_CMD_RESULT resul
 
 int commander_main(int argc, char *argv[])
 {
-	if (argc < 1) {
+	if (argc < 2) {
 		usage("missing command");
 	}