[DOCS] Replace links with intersphinx refs

Using references instead of absolute URLs has the following
advantages:

- If a target section is moved, the URL in a :ref:
  linking to it is updated automatically
- It is possible to maintain the links to the other docs
  repository in a central place (Settings.cfg). This way,
  it is possible to link to the same version of a manual
  in a lower branch (e.g. 10.4) by changing the link in
  one place

The above results in a better user experience (stay in
information for same version when linking across docs
repos) and less broken links (in the future).

Resolves: #95948
Releases: master, 10.4
Change-Id: I84d801a75424bd94b4fa15aecb17a6085af07c36
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/72145


Tested-by: core-ci <typo3@b13.com>
Tested-by: Oliver Bartsch <bo@cedev.de>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>

typo3/sysext/form/Documentation/I/Concepts/Validators/Index.rst

@@ -293,4 +293,5 @@ Override the default value within your ``form definition``:
 
 As mentioned above EXT:form implements Extbase validators. That said,
 your own validators should extend ``TYPO3\CMS\Extbase\Validation\Validator\AbstractValidator``.
-Read more about this topic in the `Extbase docs <https://docs.typo3.org/typo3cms/ExtbaseFluidBook/9-CrosscuttingConcerns/2-validating-domain-objects.html>`_.
+Read more about this topic in the Extbase documentation:
+:ref:`t3extbasebook:validating-domain-objects`.

typo3/sysext/form/Documentation/Settings.cfg

@@ -26,3 +26,4 @@ project_issues       = https://forge.typo3.org/projects/typo3cms-core/issues
 [intersphinx_mapping]
 # allow linking via intersphinx to other documentation projects
 t3coreapi     = https://docs.typo3.org/m/typo3/reference-coreapi/master/en-us/
+t3extbasebook = https://docs.typo3.org/m/typo3/book-extbasefluid/master/en-us/

typo3/sysext/seo/Documentation/Configuration/Index.rst

@@ -15,10 +15,10 @@ TypoScript Settings
 
 There are a couple of TypoScript settings that can influence the output regarding search engine optimization.
 
-* `config.pageTitleFirst <https://docs.typo3.org/m/typo3/reference-typoscript/master/en-us/Setup/Config/Index.html#pagetitlefirst>`__
-* `config.pageTitleSeparator <https://docs.typo3.org/m/typo3/reference-typoscript/master/en-us/Setup/Config/Index.html#pagetitleseparator>`__
-* `config.pageTitleProviders <https://docs.typo3.org/m/typo3/reference-typoscript/master/en-us/Setup/Config/Index.html#pagetitleproviders>`__
-* `config.noPageTitle <https://docs.typo3.org/m/typo3/reference-typoscript/master/en-us/Setup/Config/Index.html#nopagetitle>`__
+-   :ref:`config.pageTitleFirst <t3tsref:setup-config-pagetitlefirst>`
+-   :ref:`config.pageTitleSeparator <t3tsref:setup-config-pagetitleseparator>`
+-   :ref:`config.pageTitleProviders <t3tsref:setup-config-pagetitleproviders>`
+-   :ref:`config.noPageTitle <t3tsref:setup-config-nopagetitle>`
 
 Site configuration
 ==================