Oauth, gmail, docs/guide?

I've avoided this, until now, as things seemed to be "in flux" and the 
issue generating some ill will.

Downloaded 6.4.30 in anticipation, but after some fruitless searching, I 
need to ask for the location for any current docs on configuring 
fetchmail with gmail.  OAuth2 is apparently google's answer to 
everything, overthrowing 42 as the reigning champion.

Thanks for any assistance and understanding.

joe a.