Update link to multistream VideoRoom demo (#3611)

which was pointing to a renamed file

Author: fippo

html/demos/videoroom.html

@@ -64,7 +64,7 @@ <h3>Demo details</h3>
 						<div class="alert alert-info">Notice that this is the <b>original</b> VideoRoom
 						demo, and uses a different PeerConnections per each subscription: if
 						you want to test the new multistream support, instead, try the
-						<a href="mvideoroomtest.html">multistream VideoRoom demo</a>
+						<a href="mvideoroom.html">multistream VideoRoom demo</a>
 						instead. The two demos are interoperable, if you want to see how
 						different subscription mechanisms are used on the same sources.</div>
 						<p>If you're interested in testing how simulcasting or SVC can be used within