Add section about Heroku environment variables configuration

README.md

@@ -4,6 +4,22 @@ A countdown timer app.
 
 ## Build Status [![Build Status](https://secure.travis-ci.org/hackatron/sveglia.png?branch=master)](http://travis-ci.org/hackatron/sveglia)
 
+## Production environment configuration
+
+Set production environment
+
+```bash
+$ heroku config:add GOLIATH_ENV=production
+```
+
+Set production Pusher's configuration
+
+```bash
+$ heroku config:add PUSHER_APP_ID=app_id PUSHER_KEY=key PUSHER_SECRET=secret
+```
+
+replacing `app_id`, `key` and `secret` with your app's configuration details.
+
 ## Notes
 
 To start app server run