ZDoom documentation project

The ZDoom documentation project is a Doom-related wiki that attempts to save Randy Heit from the hassle of updating ZDoom's documentation whenever he adds new features, and serves as an information base for ZDoom mappers. Right now, basic ZDoom specials documentation, tricks, and other things are being added. Heit can rely on the knowledge of several dozen other people to build meaningful documentation, rather than doing all of the grunt work himself.