Update documentation links

Author: Mark Pundsack

README.md

@@ -27,7 +27,8 @@ heroku open
 
 For more information about using Node.js on Heroku, see these Dev Center articles:
 
-- [Getting Started with Node.js on Heroku](https://devcenter.heroku.com/articles/nodejs)
+- [Node.js on Heroku](https://devcenter.heroku.com/categories/nodejs)
+- [Getting Started with Node.js on Heroku](https://devcenter.heroku.com/articles/getting-started-with-nodejs)
 - [Heroku Node.js Support](https://devcenter.heroku.com/articles/nodejs-support)
 - [Building a Real-time, Polyglot Application with Node.js, Ruby, MongoDB and Socket.IO](https://devcenter.heroku.com/articles/realtime-polyglot-app-node-ruby-mongodb-socketio)
-- [Using Socket.IO with Node.js on Heroku](https://devcenter.heroku.com/articles/using-socket-io-with-node-js-on-heroku)
+- [Using WebSockets on Heroku with Node.js](https://devcenter.heroku.com/articles/node-websockets)