docs: work around ReST pedantry !cosmetic

Bump version to 2.5.dev2


new: SearchQuerySet.set_spelling_query for custom spellcheck

This makes it much easier to customize the text sent to the
backend search engine for spelling suggestions independently
from the actual query being executed.

v2.3.2 maintenance update

Release 2.4.0

v2.4.0 release candidate

Bump version to 2.4.0.dev1