[TASK] Remove famfamfam/silk note

We finally removed remaining usages with #101647
and can thus drop the info in about module. The
domain is offline meanwhile, so we backport to
v12 to avoid dead links in the backend.

Resolves: #101823
Related: #101647
Releases: main, 12.4
Change-Id: Id925da8a2dc87ca840d65b750f5025ae00fee7f0
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/80818


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