Update URL to use github.io

webaudio.github.com no longer functions as Github Pages moved to github.io a few years ago.

Author: ZingBlue

README.md

@@ -2,7 +2,7 @@
 
 This repository contains the latest editor's draft of the [W3C AudioWG](http://www.w3.org/2011/audio/)'s Web MIDI API.
 
-You can preview the current version of the master branch [here](http://webaudio.github.com/web-midi-api/).
+You can preview the current version of the master branch [here](http://webaudio.github.io/web-midi-api/).
 
 # Tests