For my final project, I chose to create a site for documentation pertaining to management of our institutional repository. As I started drafting the actual documentation to use in the template, I found that I actually really liked the workflow. Being able to edit the files locally via Notepad++, save them as needed, and only commit the changes once I was satisfied with all of the local drafts, seems like a much better approach than the online wiki-style editing of Google Docs (where it can be difficult to track many small changes over time, even using the built in tracking features.) Commit messages are an added benefit, for explanations of why changes are made. It may be somewhat overkill for text-based documentation, but the approach seems more methodological than the way we would typically approach a collaborative document.
That being said, there is undoubtably a steep learning curve when it comes to this approach, and it may not be reasonable to presume that all members of the team would be willing to learn how to use Git beyond setting up GitHub desktop, and basic Markdown tags. Over the last few years, most individuals and institutions have moved to cloud-based document editing (through Google Docs, Microsoft 365, etc.), and while GitHub does support this through the online editor, it has its own challenges, and the interface is not necessarily any more intuitive than a text editor in combination with GitHub Desktop. I believe that there is a lot of potential for this method of writing documentation, but in practice, it will depend on the technical adeptness of those involved, and willingness to explore long-term alternatives in lieu of ease of use and time constraints. For the immediate future, it may be a personal pursuit.
Additional links and blog posts that I found which might be helpful in compiling justification for using GitHub for IR documentation: