The release notes used to be an appendix in the manual. After
converting to markdown that appendix got lost. This commit
reintroduces the release notes into the manual.
(cherry picked from commit 6fc71dc563)
The `optionsDocBook` function is deprecated in nixpkgs since
nixos-23.11. This commit updates the manual and manpages to
use commonmark formatted documentation instead of the deprecated
docbook format.
