Add DNS Prefetch

Hi, I think this plugin should have the option to automatically add the CDN url to the dns-prefetch. I believe that will be a better solution than editing the functions.php

It’s seems to be really easy, maybe a function like this.

add_filter( 'wp_resource_hints',
	array(
        __CLASS__,
        'add_dns_prefetch'
    ), 10, 2 );

public static function add_dns_prefetch( $hints, $relation_type ) {
	$options = self::get_options();
	//Check options here?
	if ( 'dns-prefetch' === $relation_type ) {
	    $hints[] = $options['url'];
	}
	return $hints;
}