Improve getTreeChilds SOAP documentation for clarity (#11318)

Author: sKarki999

components/ILIAS/soap/classes/class.ilNusoapUserAdministrationAdapter.php

@@ -429,8 +429,10 @@ private function registerMethods(): void
             SERVICE_NAMESPACE . '#getTreeChilds',
             SERVICE_STYLE,
             SERVICE_USE,
-            'ILIAS getTreeChilds(): Get all child objects of a given object.' .
-            'Choose array of types to filter the output. Choose empty type array to receive all object types'
+            'ILIAS getTreeChilds(): Get all child objects of a given object. ' .
+            'Choose array of types to filter the output. Choose empty type array to receive all object types. ' .
+            'Results are filtered based on the read permissions of the given user_id. In case of an invalid user id, an empty result is returned without error. ' .
+            'Retrieve your user id first via the getUserIdBySid method and then pass it along with the parameter.'
         );
 
         $this->server->register(