I think the important question to answer is actually why should you produce good docs. Is it to inboard new devs quicker? To help experienced devs find information faster? To act as a first line of support to reduce questions from third parties using your API? Maybe a bit of everything?

It'll vary from project to project depending on the audience. There's no such thing as definitively "good docs" that would work for everyone, but you certainly can make good docs for a given project if you know what your audience needs. Ask that question first.