Add Deploy to Heroku button

[devopsmariocom]

It would be great to have own instance with few clicks.

[devopsmariocom]

I wolunteer to send MR base on https://devcenter.heroku.com/articles/heroku-button but will need to have init for firebase schema

[karuppiah7890]

Can I take this up ?

You just want the "Deploy to Heroku" button ? In that case, I think I just have to add an app.json and then modify the README.md to add a button.