I've been working on a solution to that for years now, but it hasn't been at the top of my priority list. There's some mediawiki-to-git bridges available that should be able to help with that, though, and if I ever do get one that's working such a setup would be quite ideal for showing the wiki.
And yes, there are markdown renderers available that can actually read said git repos. Even Github itself - but some offline ones too.