Update README.md for OpenWRT, enhance OpenWRT build system.

owrt/537-youtubeUnblock.nft

@@ -0,0 +1,5 @@
+#!/usr/sbin/nft -f
+# This file 
+
+add rule inet fw4 mangle_forward tcp dport 443 ct packets < 20 counter queue num 537 bypass
+insert rule inet fw4 output mark and 0x8000 == 0x8000 counter accept

owrt/youtubeUnblock.owrt

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+#!/bin/sh /etc/rc.common
+USE_PROCD=1
+
+# Openwrt procd script: https://openwrt.org/docs/guide-developer/procd-init-script-example
+# The program should be put into /usr/bin/
+# This file should be put into /etc/init.d/
+
+start_service() {
+	procd_open_instance
+	procd_set_param command /usr/bin/youtubeUnblock 537
+
+	procd_set_param nice -20
+
+	procd_set_param stdout 1
+	procd_set_param stderr 1
+
+	procd_close_instance
+}