[DOCS] Revise 12.4.x changelogs

This patch streamlines some spellings, break long code lines,
so so they are visible without horizontal scrolling and adds
more context to the RTE configuration examples.

Resolves: #103677
Releases: main, 12.4
Change-Id: I2366888a29b90ee59d76f1b8f6876eb600b730d7
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/83930


Tested-by: core-ci <typo3@b13.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Jörg Bösche <typo3@joergboesche.de>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>