I like the GitHub wiki, at least to start.

Pros:

• free
• anyone can contribute changes, but vandalism is all but impossible
• can have multiple people with commit access, and that list can be easily adjusted as needed
• history of a file is transparent, if you know the tools
• easily forkable, eg if the original owner goes AFK

Cons:

• GitHub can be overwhelming for less technical people
• many here on lemmy don't trust Microsoft (could always move to gitlab or something)
• no connection between user accounts here and there (pro for me, but I can see it as a con)

I vote one of the mods takes the initiative and creates the wiki as a test run, and slowly add non-mods as needed based on contributions. If we don't like it, moving to something else shouldn't be too annoying.