[DOCS] Add link to hooks on "Concepts > Frontend rendering" page (EXT:form)

This makes it easier for users to find the hooks.

Resolves: #102965
Releases: main, 12.4
Change-Id: Ib5a515b46165b2d941444f90c615b59e244c9d6f
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/82619


Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: core-ci <typo3@b13.com>

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

@@ -752,6 +752,9 @@ defined by:
 
 With the provided hooks, this ``FormElement`` can now be manipulated.
 
+..  seealso::
+    *   :ref:`Hooks for runtime manipulation <apireference-frontendrendering-runtimemanipulation-hooks>`
+
 If you insist on your own implementation, the abstract class ``TYPO3\CMS\Form\Domain\Model\FormElements\AbstractFormElement``
 offers a perfect entry point. In addition, we recommend checking-out ``TYPO3\CMS\Form\Domain\Model\Renderable\AbstractRenderable``.
 All of your own form element implementations must be programmed to the