[DOCS] Use speaking array keys in changelog example

Resolves: #103192
Releases: main, 12.4
Change-Id: I81c0c655b75332790243c05be14f24593c5b9d6a
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/83098


Tested-by: Oliver Bartsch <bo@cedev.de>
Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Oliver Bartsch <bo@cedev.de>