Update ADOM manual with information about distributing closed Prereleases
small issue, more legal than anything else
the manual in ADOM states that we are allowed to distribute this game freely, even though the Prereleases are closed to the public. might I suggest updating the manual in the prerelease editions? else someone could break the rules and release them, and be able to do it rather legally, and annoy the hell out of our esteemed ADOM admins.