Update README.md to state steps for a naked deploy on heroku

[hugo4711]

I had to figure out the following steps to get the instance up and running:

1. Create new app in heroku ('myapp')
2. Create a new pipeline 'myapp'
3. On command line: git clone wiki-heroku (this repo)
4. Command line: heroku login
5. Command line: heroku git:remote -a myapp
6. Command line: heroku stack:set container (to switch to docker deploy mode on heroku)
7. In heroku admin backend: Resources > Add-Ons > Add heroku-postgresql add-on
8. Command line: git push heroku 2.x:master

et voilá

[viplezer]

This saved me a lot of headache, thank you!