Fix Socket.IO URL

index.html

@@ -319,7 +319,7 @@ function linkify( selector ) {
 					{ src: 'lib/js/classList.js', condition: function() { return !document.body.classList; } },
 					{ src: 'lib/js/showdown.js', condition: function() { return !!document.querySelector( '[data-markdown]' ); } },
 					{ src: 'lib/js/data-markdown.js', condition: function() { return !!document.querySelector( '[data-markdown]' ); } },
-					{ src: 'socket.io/socket.io.js', async: true, condition: function() { return window.location.host === 'localhost:1947'; } },
+					{ src: '/socket.io/socket.io.js', async: true, condition: function() { return window.location.host === 'localhost:1947'; } },
 					{ src: 'plugin/speakernotes/client.js', async: true, condition: function() { return window.location.host === 'localhost:1947'; } },
 				]
 			});