I'd limit it to .zip and maybe .7z.
About the textfiles. If you look at the then you see that they are generating their infos pages straight from the readme files (at least I think they do). This is only possible because the readmes follow the "good old scheme" respective(?) the txt file generator:
http://www.doomworld.com/idgames/?textmaker
For possible improvements in the future I would suggest such "red line" to follow with readmes. Maybe you could create an alike textmaker.
Thanks Error for this archive!