Added RemoteUserMiddleware to middleware reference page.
Added a note regarding django.contrib.auth.authenticate.

Thanks Josh Brown for the suggestion.
Fixed #22453 -- Corrected DoesNotExist message in docs.

Thanks Eugenio Cano-Manuel.
Fixed #22457 -- Fixed contributing guide w/o github set-up

The published commnand was not working when the user did not have
the git client set-up with the public-key. Changed the contributing
guide to clone it from https instead.
Fixed spelling errors in documentation.
Fixed #22460 -- Explicity remove constraints when dropping a related field.
Fixed flake8 warnings introduced in recent commits.
Fixed #22455 -- Documented return values for send_mail and send_mass_mail
Fixed #22434 -- Retain ordering on related sliced subqueries.

Thanks maciej.pawlisz for the report, and charettes for the review.
Fixed #22220 -- Added more examples to reverse() documention.

Thanks EvilDMP for the suggestions.
Fixed #22378 -- Updated \d to [0-9]+ in urlpatterns of docs and tests.

Thanks tomwys for the suggestion.