Link to infra

This makes it clear that we deal with the set instead of the current algorithm.

Co-authored-by: Dominique Hazael-Massieux <dom@w3.org>

getusermedia.html

@@ -337,7 +337,7 @@ <h2>{{MediaStream}}</h2>
           <p>If <var>track</var> is not in <var>stream's</var> [=track set=], then abort these steps.</p>
         </li>
         <li>
-          <p>Remove <var>track</var> from <var>stream</var>'s [=track set=].</p>
+          <p>[=set/Remove=] <var>track</var> from <var>stream</var>'s [=track set=].</p>
         </li>
         <li>
           <p>[= Fire a track event =] named {{removetrack}} with