EDD SL add discount code to email renewal link

file.php

<?php // DO NOT COPY THIS LINE

// add discount code Software Licensing renewal email {renewal_link} tag
function edd_sl_renewal_link_discount( $url ) {
	$url = $url . '&discount=DISCOUNTCODE';
	return $url;
}
add_filter( 'edd_sl_renewal_link', 'edd_sl_renewal_link_discount' );