Add Part 2 - Serial IO lesson (#88)

* Add Serial Link lesson to part 2

* Move serial link standalone demo to separate file

* Add serial link Unbricked integration

* Update src/part2/serial-link.md

* Update src/part2/serial-link.md

* Update src/part2/serial-link.md

* Update src/part2/serial-link.md

* Update src/part2/serial-link.md

* Update src/part2/serial-link.md

* Update src/part2/serial-link.md

* Update src/part2/serial-link.md

* Update src/part2/serial-link.md

* Update src/part2/serial-link.md

* Update src/part2/serial-link.md

Co-authored-by: Antonio Vivace <[email protected]>

* Update src/part2/serial-link.md

Co-authored-by: Antonio Vivace <[email protected]>

* add intro text

* add build script for the cicd

* implement suggestions and fix discussions

* older hardware.inc

* update build commands

---------

Co-authored-by: Antonio Vivace <[email protected]>

Author: quinnyo

src/SUMMARY.md

@@ -31,6 +31,7 @@
 - [Bricks](part2/bricks.md)
 - [Title Screen](part2/title-screen.md)
 - [Decimal Numbers](part2/bcd.md)
+- [Serial Link](part2/serial-link.md)
 - [Work in progress](part2/wip.md)
 
 # Part III — Our second game

src/part2/serial-link.md

@@ -0,0 +1,6 @@
+#!/bin/sh
+
+rgbasm -o sio.o sio.asm
+rgbasm -o main.o main.asm
+rgblink -o unbricked.gb main.o sio.o
+rgbfix -v -p 0xFF unbricked.gb