>  If that premise turns out to be false, we should think seriously about whether this makes the docs less approachable for everyday users.

We have not done such a thing for any other feature of the language. I think that since this is now a part of the language, it has all the right to be part of the documentation (possibly in some phased process). The contrary will be extremely unfair to the feature and to the PEP process: not a single other case had to fight separately to be included in the language and the documentation. 

And we even have an analogous case: keyword-only argument.