[TASK] Add new topic to FAQ

How to migrate old image fields to new FAL fields?

Resolves: #59811
Change-Id: I01a81ba753584b0d8e11c834ef40368ed429f52d
Reviewed-on: https://review.typo3.org/31105
Reviewed-by: Armin Ruediger Vieweg
Tested-by: Armin Ruediger Vieweg