We are currently going through a rethink of our documentation (not for customers, just our internal processes, tools, etc.). Currently we have a docs directory in the root of our project repository which holds a bunch of markdown files, but we are beginning to grow out of this. Keeping links accurate and update to date isn't too much of a challenge, it's the barrier to entry. Filing a PR to make a minor documentation change is just too much. We could have the documentation in a separate repository, but if we are going to be making this leap, we want to be sure we are using the right tools for the jobs.
The way we see it, we are going to end up requiring at least 2 different types of documentation. The first is our deep documentation of our tools. This explains exactly what it is, how it works, etc. and is designed for people who want to work on these sorts of tools, not with them. The second is a quick fire Q&A. "I'm having issue X, how do I fix it?" Think StackOverflow.
So, what does your team do for these challenges? How effective is your solution? What do you think would be better?