Create mcx360_and_mcpe.markdown

It might be clearer and less spammy to have all Xbox 360 and Pocket Edition rules within one file. I realise there should only be one # Title per file, but this seemed like the clearest and less spammy way of presenting a large set of rules. The alternative is to split these into 3 different folders/files: mcx360_and_mcpe, minecraft:_xbox360_edition and minecraft:_pocket_edition.