Discussion on: How do you document your code?

I've used Slate in the past for API documentation. It works well for generating a slick HTML interface from Markdown files. I'm sure you could just use it for non-API applications.

For other projects I use static site generators. Anything that let's me write in Markdown and translate to HTML, and deploy from a repo so it's readily available to anyone to edit. GatsbyJS is my personal goto, but honestly you can achieve this with other frameworks such as Hugo, Jekyll, or a few React ones.

You can build out a CMS interface for these static repos using Netlify CMS if you have non-developers who feel uncomfortable using git or Markdown.

And you can host everything on a private repo, like a custom GitLab install, and leverage their CI tools to do the build process (so you're not paying monthly fees to cloud-based deployment). And then ideally deploy to a private or local server.