Fixed #21665 -- Documented that changes in assertRedirects may be required given new URL escaping behavior.

Thank pdc for the report.
Fixed #22247 -- Replaced "upstream" with "downstream" in cache docs.

Thanks valgarv at gmx.net for the report.
Fixed #22048 - Enhanced docs to cover nonexistent one-to-one relationships.

Thanks EvilDMP for the suggestion.
Removed versionadded/changed annotations for 1.6.
Fixed typo in error message in django.contrib.sitemaps.
Fixed #22293 -- Avoided renaming many-to-many tables to themselves.

Fixed this for both implementations of _alter_many_to_many, instead of
in `alter_db_table` itself (more implementations).
Fixed #22257 -- Added file output option to dumpdata command.
Merge pull request #2465 from coder9042/ticket_22258

Fixed #22257 -- Added file output option to dumpdata command.
Fixed #22300 -- Fixed crash in migrations when changing non-relational field to relational.