Not many wiki site engines based on Markdown work directly from git as cleanly as this.
There's a few of them though, such as this old Ruby lang standby with a decade's worth of features that a decade ago was a way to host your same GitHub Pages site locally, supporting SSO:
https://tina.io/ tinacms is very modern & well built, git markdown typescript. and headless or with template components.
it's such an epic feat, how programmers have grown up to manage source over time & changes. i very much hope this richness cam extend beyond code some day, stop being arbitrary UI we craft & become good data structures that transcend each application.
It doesn't limit itself to markdown, nor to git (you can use darcs, hg, or even sqlite). A bit long in the tooth, though -- I stopped working on it once spam started to make self-hosted public wikis untenable.
I really enjoyed Gollum for awhile, but I'm not a Rubyist, and past a certain point, every time I tried to run it or Jekyll I got dependency problems that I'd eventually solve, but without understanding. It was undoubtedly user error; I should definitely have learned and used rvm or something.
It should be noted that goolum is AFAIK still the backend behind GitLabs Wikis. It works quite well Ime and was easy to setup/use for basic Markdown Documents.
There's a few of them though, such as this old Ruby lang standby with a decade's worth of features that a decade ago was a way to host your same GitHub Pages site locally, supporting SSO:
https://github.com/gollum/gollum
https://github.com/gollum/gollum/wiki/Gollum-via-Rack-and-CA...