* Introduce a guides.xml, the presence of this file
  triggers the new rendering.
* Remove old Settings.cfg, was only used for Sphinx

Attention: Backport needs manual changes to the guides.xml.

Resolves: #103334
Releases: main, 12.4, 11.5
Change-Id: If2086510e19ca5dc682d9ff0e45c545a458bdfc1
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/83325


Tested-by: Lina Wolf <112@linawolf.de>
Tested-by: Chris Müller <typo3@krue.ml>
Reviewed-by: Lina Wolf <112@linawolf.de>
Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Chris Müller <typo3@krue.ml>