Updated argument name

misc.cpp

@@ -99,7 +99,7 @@ void print_help()
 	printf("repository: https://github.com/wangyu-/udp2raw-tunnel\n");
 	printf("\n");
 	printf("usage:\n");
-	printf("    run as client : ./this_program -c -l local_listen_ip:local_port -r server_ip:server_port  [options]\n");
+	printf("    run as client : ./this_program -c -l local_listen_ip:local_port -r server_host:server_port  [options]\n");
 	printf("    run as server : ./this_program -s -l server_listen_ip:server_port -r remote_host:remote_port  [options]\n");
 	printf("\n");
 	printf("common options,these options must be same on both side:\n");