I am trying to form a minimal webpage with the help of simple .md files. I have heard that GitHub and GitLab have "pages" feature and I want to use least possible extra tools or plugins. What should my git repository look like if I want to design a minimal page?
If you want to publish markdown then you can use Jekyll (just one possibility), and follow the [Create a GitLab Pages website from scratch](https://docs.gitlab.com/ee/user/project/pages/getting_started/pages_from_scratch.html) guide.
I think you can just replace `index.html` with `index.md` and your markdown.