[DOCS] Properly document modulename registration for EXT:adminpanel

The documentation contained a wrong registration code example,
which now uses the proper array depth level notation.

Releases: main, 12.4, 11.5
Resolves: #104105
Change-Id: Idb3c9b0e723af2f1bb579bc304637497e1272e36
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/84709


Tested-by: Garvin Hicking <gh@faktor-e.de>
Reviewed-by: Lina Wolf <112@linawolf.de>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Lina Wolf <112@linawolf.de>
Reviewed-by: Garvin Hicking <gh@faktor-e.de>

typo3/sysext/adminpanel/Documentation/Extending/Index.rst

@@ -44,10 +44,8 @@ To create your own Admin Panel module
    .. code-block:: php
 
       $GLOBALS['TYPO3_CONF_VARS']['EXTCONF']['adminpanel']['modules']['mynamespace_modulename'] = [
-          'module' => [
-              \Your\Namespace\Adminpanel\Modules\YourModule::class,
-              'before' => ['cache'],
-          ]
+          'module' =>  \Your\Namespace\Adminpanel\Modules\YourModule::class,
+          'before' => ['cache'],
       ];
 
 Using `before` or `after` you can influence where your module will be