Thanks Darrin, that sounds like a really good idea. I don't know why I didn't think about it. I'll look it up and let everyone know which one I choose in case anyone else is interested.

Sounds like you want a wiki. MediaWiki is popular, but there are several
others that are also popular and well regarded. Many people use wikis
for internal company documentation. Alan Dayley was just talking about
using one at his work.

I'm sure others here can give you good specific suggestions.