Describe what the files we build are

[Rangi42]

Currently the pret projects all have a README listing "the following ROM(s)" they build, with their GoodTools-conventional names and SHA-1 hashes.

That info was sufficient for people used to the ROM scene, but for those unfamiliar with codes like "(UE)" and "[C]", a brief explanation of each file's identify would help (e.g. "The US English release of Pokémon Crystal, revision 1.1".

Furthermore, we now build files besides the GoodTools-namable ROMs (VC patches and leaked debug ROMs). "CRYSTAL_ps3_010328d.bin" and "CGBBYTE1.784.patch" are meaningless unless you know or can research them.

If this is done for pokecrystal, we can follow up for the other pret repos, even beyond Gen 1+2.