Use `LOOKUP_SEP` in `get_or_create`.
Fixed #20282 -- Typo in WSGI docs.
Fixed #20286 - Typo in static files docs.

Thanks bmispelon.
Fixed #20285 - Added missing commas in translation docs.

Thanks cody.j.b.scott@
Complemented documentation following commit be9ae693c

Refs #17840. Thanks Carl Meyer for noticing the omission.
Explained the pattern for special methods compatibility.
Fixed #20276 -- Implemented __bool__ for MergeDict

MergeDict evaluates now to False if all contained dicts are empty.
Thanks til for the report and the initial patch.
Fix != operations on lazy objects.