I’ve been looking for a folder based wiki - was this a custom tool you made?
If you want just markdown > website with some administration to edit you can use pretty much any flat file CMS. Kirby CMS is highend but you need buy license. Grav is ok open-source option but i don't like the admin part too much but its atleast active. You can find many more https://github.com/ahadb/flat-file-cms but flatfile cms often becomes pet project that people stop maintain so watch out for activity.