[TASK] RTE: Update some references to core documentation

Releases: master
Resolves: #62843
Change-Id: Ieb5b71993f009ca4c7fa2c9626a2d651ebde3bdd
Reviewed-on: http://review.typo3.org/33973
Reviewed-by: Stanislas Rolland <typo3@sjbr.ca>
Tested-by: Stanislas Rolland <typo3@sjbr.ca>