[chore] Update the license of the chat example (#3410)

There was no obvious reason to use BSD instead of MIT for that very basic chat app.

Closes #3411

Author: grant

examples/cluster-nginx/server/package.json

@@ -5,7 +5,7 @@
   "main": "index.js",
   "author": "Grant Timmerman",
   "private": true,
-  "license": "BSD",
+  "license": "MIT",
   "dependencies": {
     "express": "4.13.4",
     "socket.io": "^1.7.2",