d/changelog: Add missing changelog entry

Signed-off-by: Niels Thykier <niels@thykier.net>
T::L: Check manual references as a part of test_check_desc

Check that references are well-formed and (for manuals) is in our
table of references.  Furthermore, attempt to detect uses of URLs
that could be replaced by a manual reference instead.

Signed-off-by: Niels Thykier <niels@thykier.net>