Add Discount Code Menu Item to Paid Memberships Pro 2.0

add-my-discount-code.php

<?php
/**
 * Add discount code menu item under "Memberships" admin menu.
 * Add this code to your PMPro Customizations Plugin - https://www.paidmembershipspro.com/create-a-plugin-for-pmpro-customizations/
 */
function my_pmpro_menu_add_discounts() {
  add_submenu_page( 'pmpro-dashboard', __( 'Discount Codes', 'paid-memberships-pro' ), __( 'Discount Codes', 'paid-memberships-pro' ), 'pmpro_discountcodes', 'pmpro-discountcodes', 'pmpro_discountcodes' );
}
add_action( 'admin_menu', 'my_pmpro_menu_add_discounts' );