Update spec url

Author: jsor

README.md

@@ -4,7 +4,7 @@ HTTP Client Hints
 [![Build Status](https://travis-ci.org/jsor/http-client-hints.svg?branch=master)](http://travis-ci.org/jsor/http-client-hints?branch=master)
 [![Coverage Status](https://coveralls.io/repos//jsor/http-client-hints/badge.svg?branch=master)](https://coveralls.io//jsor/http-client-hints?branch=master)
 
-Utilities for working with [HTTP Client Hints](https://.com/igrigorik/http-client-hints).
+Utilities for working with [HTTP Client Hints](http://httpwg.org/http-extensions/client-hints.html).
 
 Installation
 ------------