Private owned retailer: used Sharepoint and / or word documents on a shared network drive. This didn't work very well, but it ticked the "I did it" / corporate compliance boxes.
University: we use OneNote notebooks for each team. It's stored on a file share, and since everyone already uses Windows 10 / O365, it's an easy thing for our security concerns. It's also auto-backed up to the cloud (O365). It's also easy for business users / BA's to view and contribute to. Downsides: it's hard to flag info as out of date, or notify people of changes.
Healthcare provider: we used Markdown / Git. This worked because there was a single (mono) git solution for the entire org. Technically there was an SVN thing too, but the org was working to actively remove that / transfer source code to BitBucket. We required each project to have a README.md. This file included what the project did, and all the info a new analyst needs to know to get up and running: how to build the project, what servers it deployed to, what testing / production URL's applied to the project, what tools you installed on your local machine, etc.
We had a separate repository for "standards" that applied to all projects or across different global teams (think "internal" - EPIC, Sharepoint, etc teams and "external" product teams). These were just markdown files that contained policy info, best practices, libraries to use, etc. There was a "standards" team made up of a dozen individuals from separate teams that met quarterly to make updates to these standards. Changes were managed in Git and any issues were created there as well. It worked pretty well, since policy / standard changes tend to move slowly in large orgs. It also gave all teams visibility to the policies so they were all on the same page.