Merge topic 'doc-4.0-relnotes'

5fdd917f8a Help: Update Sphinx versionadded directives for 4.0 release
fb69ed725e Help: Organize and revise 4.0 release notes
1191647a0e Help: Consolidate 4.0 release notes

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !10288