R1:7be671fb0750

Update "Autoclose" documentation to focus on "Permanent Refs" instead

Summary:
Depends on D20433. Ref T13277. Since "Autoclose" no longer exists, update the documentation.

Currently, this documentation focuses a lot on troubleshooting because users historically had a lot of trouble with figuring out why things were or were not autoclosing. I haven't seen any real confusion about this in years, so I suspect we may have improved the import pipeline and/or UI to make this less of a problem.

It's also…