Doc clarification - Running on Heroku

[demondragong]

Hi! Just managed to install the tasty umami on heroku thanks to the instructions on this page: https://umami.is/docs/running-on-heroku

I only struggled with creating the database tables because the script could not be found... because I had not deployed the app...

I think it wouldn't hurt to add a 7th step in the Website section of this guide (maybe "Click the Deploy > Manual Deploy > Deploy Branch button.") as currently it seems like you're done once you have connected to your github repo.

Thanks for this beautiful tool and keep up the good work!