[TASK] Enhance documentation for integration of html-sanitizer

* remove superfluous `}` literal from PHP example
* add "Troubleshooting" section of reported side-effects
* add "Logging" section, supporting to spot those side-effects

Resolves: #94797
Releases: master, 11.3, 10.4, 9.5
Change-Id: I4b154c849b158d920b380f40d1415762d227ae6d
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/70440


Tested-by: Oliver Bartsch <bo@cedev.de>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Oliver Hader <oliver.hader@typo3.org>
Reviewed-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Oliver Hader <oliver.hader@typo3.org>