[DOCS] Remove Linkvalidator documentation "Next Steps"

The chapter "Next Steps" contained very little information.

Resolves: #92719
Releases: master
Change-Id: I2cacf4081c47bbb35f4e89239dfc9ae0b78253db
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/66268


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Björn Jacob <bjoern.jacob@tritum.de>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Björn Jacob <bjoern.jacob@tritum.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>