[TASK] Update spelling of the word webhooks

Following the commonly used spelling of the word "webhook", this change
updates the headline of the Reactions backend module.

Resolves: #99259
Releases: main
Change-Id: I73ecf994f7221a70de801a7c3e1bf6a92a23f006
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/76913


Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Tested-by: Oliver Klee <typo3-coding@oliverklee.de>
Tested-by: Benni Mack <benni@typo3.org>
Tested-by: Chris Müller <typo3@krue.ml>
Reviewed-by: Chris Müller <typo3@krue.ml>