Remove link to face tracking demo (webrtc#1031)

As per webrtc#1022.

Author: samdutton

index.html

@@ -95,8 +95,6 @@ <h3 id="getusermedia">getUserMedia</h3>
 
       <p><a href="src/content/getusermedia/volume/">Audio-only getUserMedia() displaying volume</a></p>
 
-      <p><a href="src/content/getusermedia/face/">Face tracking, using getUserMedia and canvas</a></p>
-
       <p><a href="src/content/getusermedia/record/">Record stream</a></p>