feat(developer): Add new ExApp OpenAPI scope

Signed-off-by: provokateurin <kate@provokateurin.de>

Author: provokateurin

developer_manual/app_publishing_maintenance/app_upgrade_guide/upgrade_to_30.rst

@@ -100,6 +100,7 @@ Added APIs
 - ``OCA\Files_Trashbin\Trash\ITrashItem::getDeletedBy`` should return the user who deleted the item or null if unknown
 - ``OCP\IUser::getPasswordHash`` should return the password hash of the user
 - ``OCP\IUser::setPasswordHash`` should set the password hash of the user
+- ``OCP\AppFramework\Http\Attribute\OpenAPI::SCOPE_EX_APP`` attribute is available for scoping APIs only to be used by ExApps.
 
 Changed APIs
 ^^^^^^^^^^^^