I would like to add that Bookstack seems popular though I know not very much about it.

https://www.bookstackapp.com/

This article is a great comparison of self-hosted wiki software including Dokuwiki, Bookstack and Wiki.js

https://xtom.com/blog/self-hosted-wiki/

Others like Joplin seem to have been mentioned plenty enough! It has been a blast reading other people's responses, thanks everyone. Feels good to contribute to a general pool of information that isn't owned by some enshittifying company. Threads with so much good information like this make me want a really easy way to turn lemmy comment threads into wiki-like articles associated with the relevant sub-lemmy that link back and forth to the source comments (and their external sources of course). The mods of the sub-lemmy could have control over approving new wiki pages.