Add a "Deploy to Heroku" button.

You can test the button from here:
https://github.com/knu/huginn/tree/heroku_button#deployment
Also worth linking to https://github.com/cantino/huginn/wiki/Run-Huginn-for-free-on-Heroku and saying:

    Heroku's free plan limits the number of database rows that you can have to 10,000, so you should
    be sure to set a low event retention schedule for your agents.