[DOCS] Remove section using version constraint installing EXT:linkval…

…idator

This section is not necessary as the version best suitable is
installed by Composer automatically. Therefore, it is removed.
This also relieves us from adjusting outdated versions.

Resolves: #100881
Releases: main, 12.4
Change-Id: Id7f65c743159ebb3715f3bfa3b01aa38d052f843
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/79076
Tested-by: Lina Wolf <112@linawolf.de>
Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Lina Wolf <112@linawolf.de>

typo3/sysext/linkvalidator/Documentation/Administration/Index.rst

@@ -15,13 +15,6 @@ requiring the package `typo3/cms-linkvalidator`:
 
     composer require typo3/cms-linkvalidator
 
-If you are using Composer and not working with the latest version of TYPO3
-you will need to add a version constraint:
-
-.. code-block:: bash
-
-    composer require typo3/cms-linkvalidator:"^10.4"
-
 If you want to use the LinkValidator in the Scheduler, the system extension
 :file:`scheduler` also needs to be installed: