How to add a hint text e.g. for discounts on shopping cart and checkout page?

add_action( 'woocommerce_proceed_to_checkout', 'rabatt_text_eins', 1 );
add_action( 'woocommerce_review_order_before_submit', 'rabatt_text_eins', 1 );
function rabatt_text_eins() {
  $text = "Inhaltstext";
   echo $text;
}