WooCommerce Snippet: Añadir texto o html en la parte superior del checkout (finalizar compra)

add_checkout_top_text.php

/**
 * This WordPress code snippet adds some text or html at the top of the checkout page of your WooCommerce
 *
 * Author: Oscar Abad Folgueira
 * Author URI: http://www.oscarabadfolgueira.com
 *
 * You can copy this snippet and paste in your functions.php or you can build your own plugin
 */
 
add_action( 'woocommerce_before_checkout_form', 'add_checkout_top_text', 11 );
function add_checkout_top_text() {
    wc_print_notice( '<h3 style="color:red;">Solo te queda un paso más para finalizar la compra!!</h3>' );
}