send_early_hints

Early Hints is an HTTP/2 status code that indicates hints to help a client start making preparations for processing the final response.

If the env contains `rack.early_hints` then the server accepts HTTP2 push for link headers.

The `send_early_hints` method accepts a hash of links as follows:

send_early_hints("link" => "</style.css>; rel=preload; as=style,</script.js>; rel=preload")

If you are using `javascript_include_tag` or `stylesheet_link_tag` the Early Hints headers are included by default if supported.