Allows to change shipment description when on TTN creating. Default value depends on option Default shipment description in plugin settings,
Example of usage:
/** * @var string $description - Current description (provided from plugin settings) * @var \WC_Order $order - WooCommerce order for which TTN creating */ add_filter('wcus_ttn_form_description', function ($description, $order) { return 'Custom description'; }, 10, 2);