Merge topic 'doc-3.28-relnotes'

5df79d1930 Help: Update Sphinx versionadded directives for 3.28 release
4eb2386901 Help: Organize and revise 3.28 release notes
32f3966521 Help: Consolidate 3.28 release notes
2c4f579124 Help: Fix versionadded indentation in cmake-generator-expressions(7) manual

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !8855