We have a big mix of markdown files / swagger docs / docstrings / other html/css/js docs (react storybook).<p>And are looking to centralize them in a way that allows for: Github authentication, search / indexing, internal commenting / discussion.
I built an internal wiki replacement: nurtch.com<p>It provides ability to create documents with markdown text, images, executable code and output all within single document. Although it's optimized for infrastructure runbooks, it can be used for any internal documentation. Reports, metrics, onboarding guides, design documents etc.<p>If you don't foresee any need for executable code then it's probably not for you. I have seen teams use Dropbox paper, Media wiki, and sometimes Gdocs for static internal documentation.
We use a WordPress website with a plugin to make it into a knowlegebase wiki. First we used a plugin called UserPress. Then we moved to Zhen documsntation. Now we use a Plugin called Helpie. It's Front-end editor is good use for internal documentation.