Add port variable

Add missing port variable.
webtorrent · FluorescentHallucinogen · Mar 25, 2016 · Mar 25, 2016 · Mar 25, 2016 · Mar 25, 2016
commit 9c9bfc9119dd3071be1af3e879ab757292b0996b
diff --git a/docs/api.md b/docs/api.md
@@ -299,6 +299,7 @@ Here is a usage example:
 ```js
 var client = new WebTorrent()
 var torrentId = 'magnet:?xt=urn:btih:6a9759bffd5c0af65319979fb7832189f4f3c35d&dn=sintel.mp4&tr=wss%3A%2F%2Ftracker.btorrent.xyz&tr=wss%3A%2F%2Ftracker.fastcast.nz&tr=wss%3A%2F%2Ftracker.openwebtorrent.com&tr=wss%3A%2F%2Ftracker.webtorrent.io&ws=https%3A%2F%2Fwebtorrent.io%2Ftorrents%2Fsintel-1024-surround.mp4'
+var port = 5003
 
 client.add(torrentId, function (torrent) {
   // create HTTP server for this torrent