Fixed typo in docs/ref/checks.txt
Fixed #22141 -- Added a spelling checker for documentation.
Fixed #21863 -- supplemented get_lookup() with get_transform()

Also fixed #22124 -- Expanded explanation of exactly what is going on in
as_sql() methods.
Fixed #22034 -- Added a specific set of relation checks for GenericInlineModelAdmin.

Thanks to jwa for the report.
Split model.fields.related.