Doc: Fix MSYS2 shortcut names in README.md
Doc: Fix MSYS2 shortcut names in README.md

jeremyherbert/mgba,sergiobenrocha2/mgba,sergiobenrocha2/mgba,Anty-Lemon/mgba,libretro/mgba,Anty-Lemon/mgba,Iniquitatis/mgba,Anty-Lemon/mgba,Iniquitatis/mgba,sergiobenrocha2/mgba,fr500/mgba,jeremyherbert/mgba,sergiobenrocha2/mgba,libretro/mgba,jeremyherbert/mgba,mgba-emu/mgba,jeremyherbert/mgba,Anty-Lemon/mgba,sergiobenrocha2/mgba,libretro/mgba,libretro/mgba,mgba-emu/mgba,fr500/mgba,mgba-emu/mgba,fr500/mgba,fr500/mgba,Iniquitatis/mgba,Iniquitatis/mgba,mgba-emu/mgba,libretro/mgba