Before back fill, clean up.

- Add suggested CVE format to template
- Move Security to the top of release notes
- Fix headings
- Update all existing CVE notes to match template

Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>

Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>

Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>

Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>

Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>

Co-authored-by: Ondrej Baranovič <nulano@nulano.eu>

- Include CVE link in title (via @hugovk)
- Retro-add release notes for 2.3.2, 2.5.2 for CVE-2014-3589

Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>

Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>

Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>

Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>

Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>

Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>

- Back fill release notes for 3.1.1
- Add credits to 2.3.2, 2.5.2

- Restore accidentally overwritten contents
- Update to match updated template

- Categorized previously uncategorized notes under ``Other Changes``
- TODO: Fix categorization of notes in ``Other Changes`` that belong in other categories

Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>