I've been thinking a lot about documentation and how to get a user up to speed on a code base as quickly and effortlessly (on the part of the user) as possible.

I know "best" can be somewhat arbitrary or subjective, but use whichever metric you think is most relevant (organization, clarity, etc...). And, if you'd like, let me know what you think "best" should mean in relation to documentation quality.

Also, I know this question has been asked before, but those threads are all several years old, so in that time the documentation pool has obviously changed (and hopefully improved).