[DOCS] Switch Low Level documentation to PHP-based rendering

* Introduce a guides.xml, the presence of this file
  triggers the new rendering.
* Remove superfluous genindex, it is not supported anymore
* Remove old Settings.cfg, was only used for Sphinx

Attention: Backports need manual changes to the guides.xml.

Resolves: #103329
Releases: main, 12.4, 11.5
Change-Id: I7ed40a0f5ce1d96003e78ac8860e6dda4c12b225
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/83416
Reviewed-by: Lina Wolf <112@linawolf.de>
Tested-by: Lina Wolf <112@linawolf.de>
Tested-by: core-ci <typo3@b13.com>

typo3/sysext/lowlevel/Documentation/BackendModules/Configuration.rst

@@ -36,7 +36,7 @@ The Configuration module displays various configuration settings:
 - :ref:`Global configuration <t3coreapi:typo3ConfVars>` (:php:`$GLOBALS['TYPO3_CONF_VARS']`)
 - :doc:`Table configuration array <t3tca:Index>` (:php:`$GLOBALS['TCA']`)
 - :ref:`Registered services <t3coreapi:services>` (:php:`$GLOBALS['T3_SERVICES']`)
-- :doc:`Skinning styles <t3skinning:Index>` (:php:`$GLOBALS['TBE_STYLES']`)
+- Skinning styles (:php:`$GLOBALS['TBE_STYLES']`)
 - :ref:`User settings configuration <t3coreapi:user-settings>` (:php:`$GLOBALS['TYPO3_USER_SETTINGS']`)
 - :ref:`Table permissions by page type <t3coreapi:page-types-intro>`
 - :ref:`User settings <t3coreapi:be-user-configuration>` (:php:`$GLOBALS['BE_USER']->uc`)

typo3/sysext/lowlevel/Documentation/Includes.rst.txt

@@ -1,34 +1 @@
-.. More information about this file:
-.. https://docs.typo3.org/m/typo3/docs-how-to-document/main/en-us/GeneralConventions/FileStructure.html#includes-rst-txt
-
-.. ----------
-.. text roles
-.. ----------
-
-.. role:: aspect(emphasis)
-.. role:: bash(code)
-.. role:: html(code)
-.. role:: js(code)
-.. role:: php(code)
-.. role:: rst(code)
-.. role:: sep(strong)
-.. role:: sql(code)
-
-.. role:: tsconfig(code)
-   :class: typoscript
-
-.. role:: typoscript(code)
-.. role:: xml(code)
-   :class: html
-
-.. role:: yaml(code)
-
-.. default-role:: code
-
-.. ---------
-.. highlight
-.. ---------
-
-.. By default, code blocks use PHP syntax highlighting
-
-.. highlight:: shell
+..  You can put central messages to display on all pages here

typo3/sysext/lowlevel/Documentation/Index.rst

@@ -96,4 +96,3 @@ pages and records.
    :hidden:
 
    Sitemap
-   genindex

typo3/sysext/lowlevel/Documentation/guides.xml

@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<guides xmlns="https://www.phpdoc.org/guides" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+        xsi:schemaLocation="https://www.phpdoc.org/guides ../vendor/phpdocumentor/guides-cli/resources/schema/guides.xsd"
+        links-are-relative="true">
+    <extension class="\T3Docs\Typo3DocsTheme\DependencyInjection\Typo3DocsThemeExtension"
+               project-home="https://extensions.typo3.org/extension/lowlevel/"
+               project-contact="https://typo3.slack.com/archives/C025BQLFA"
+               project-repository="https://github.com/typo3/typo3"
+               project-issues="https://forge.typo3.org/projects/typo3cms-core/issues"
+               edit-on-github-branch="12.4"
+               edit-on-github="typo3/typo3"
+               edit-on-github-directory="typo3/sysext/lowlevel/Documentation/"
+               typo3-core-preferred="12.4"
+               interlink-shortcode="typo3/cms-lowlevel"
+    />
+    <project title="Low Level"
+             release="12.4"
+             version="12.4"
+             copyright="since 1997 by the TYPO3 contributors"
+    />
+</guides>