[1.5.x] Added dates to release notes.

Backport of 0fd23545db from master
[1.5.x] Fixed #23431 -- Allowed inline and hidden references to admin fields.

This fixes a regression introduced by the 53ff096982 security fix.

Thanks to @a1tus for the report and Tim for the review.

refs #23329.

Backport of 342ccbd from master
[1.5.x] Fixed #23604 -- Allowed related m2m fields to be references in the admin.

Thanks Simon Charette for review.

Backport of a24cf21722 from master
[1.5.x] Added release dates to release notes.

Backport of 9dc782b631 from master
[1.5.x] Update version numbers for bugfix release.
merged django 1.5.11 into bulk_insert branch

Merge tag '1.5.11' of https://github.com/django/django into bulk_insert-return-IDs

Tag 1.5.11