Add Category descriptions to menus

if ( function_exists('wp_nav_menu') ) {
    add_theme_support( 'nav-menus' );
    register_nav_menus( array( 'primary-menu' => __( 'Primary Menu' ), 'secondary-menu' => __( 'Secondary Menu' ) ) );

    // Add category descriptions
    if ( get_option('woo_menu_desc') == "true" ) {
        add_filter('walker_nav_menu_start_el', 'description_in_nav_el', 10, 4);
        function description_in_nav_el($item_output, $item, $depth, $args) {
            return preg_replace('/(<a.*?>[^<]*?)</', '$1' . "<br /><span>{$item->post_content}</span><", $item_output);
        }
    }

}