Change WordPress admin area footer text

change-wp-admin-footer-text.php

<?php
/**
 * Add into "functions.php" file.
 */

function my_change_admin_footer_text($text)
{
	$text = '<em>Thank you for creating with <a href="#" target="_blank">Theme Name</a> Custom <a href="http://wordpress.org" target="_blank">WordPress</a> Theme.</em>';
	return $text;
}

add_filter('admin_footer_text', 'my_change_admin_footer_text', 10, 1);