[TASK] Add documentation for ClickMenuController code removal

Follow up to https://review.typo3.org/32905

Resolves: #61781
Releases: master
Change-Id: I5fe7107795124c297d837dfe01b06b83bd5b6373
Reviewed-on: http://review.typo3.org/32912
Reviewed-by: Benjamin Mack <benni@typo3.org>
Tested-by: Benjamin Mack <benni@typo3.org>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>