[DOCS] Add hint to EXT:redirects regarding LinkHandler

Using constants in the LinkHandler TSConfig does not work in the
redirects module.

Resolves: #103205
Releases: main, 12.4, 11.5
Change-Id: I29dda248c5e80e077d53c8ecead9fb29fd041f76
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/84826


Tested-by: core-ci <typo3@b13.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>