Remove public mention of Heroku setup

This isn't really something we want to support

app.json

@@ -1,15 +0,0 @@
-{
-  "name": "WagtailBakeryDemo",
-  "description": "WagtailBakeryDemo",
-  "repository": "https://github.com/wagtail/bakerydemo",
-  "keywords": ["wagtail", "django"],
-  "env": {
-    "DJANGO_DEBUG": "off",
-    "DJANGO_SETTINGS_MODULE": "bakerydemo.settings.production",
-    "DJANGO_SECURE_SSL_REDIRECT": "on"
-  },
-  "scripts": {
-    "postdeploy": "django-admin migrate && django-admin load_initial_data && echo 'from wagtail.images.models import Rendition; Rendition.objects.all().delete()' | django-admin shell"
-  },
-  "addons": ["heroku-postgresql:hobby-dev"]
-}

readme.md

@@ -34,12 +34,10 @@ This demo is aimed primarily at developers wanting to learn more about the inter
 - [Vagrant](#setup-with-vagrant)
 - [Docker](#setup-with-docker)
 - [Virtualenv](#setup-with-virtualenv)
-- [Heroku](#deploy-to-heroku)
 
 If you want to see what Wagtail is all about, we suggest trying it out through [Gitpod](#setup-with-gitpod).
 If you want to set up Wagtail locally instead, and you're new to Python and/or Django, we suggest you run this project on a Virtual Machine using [Vagrant](#setup-with-vagrant) or [Docker](#setup-with-docker) (whichever you're most comfortable with). Both Vagrant and Docker will help resolve common software dependency issues.
 Developers more familiar with virtualenv and traditional Django app setup instructions should skip to [Setup with virtualenv](#setup-with-virtualenv).
-If you want a publicly accessible demo site, [deploy to Heroku](#deploy-to-heroku).
 
 ## Setup with Gitpod
 
@@ -165,53 +163,6 @@ To set up your database and load initial data, run the following commands:
 
 Log into the admin with the credentials `admin / changeme`.
 
-## Deploy to Heroku
-
-If you want a publicly accessible demo site, use [Heroku's](https://heroku.com) one-click deployment solution to the free 'Hobby' tier:
-
-[![Deploy](https://www.herokucdn.com/deploy/button.svg)](https://heroku.com/deploy?template=https://github.com/wagtail/bakerydemo)
-
-If you do not have a Heroku account, clicking the above button will walk you through the steps
-to generate one. At this point you will be presented with a screen to configure your app. For our purposes,
-we will accept all of the defaults and click `Deploy`. The status of the deployment will dynamically
-update in the browser. Once finished, click `View` to see the public site.
-
-Log into the admin with the credentials `admin / changeme`.
-
-To prevent the demo site from regenerating a new Django `SECRET_KEY` each time Heroku restarts your site, you should set
-a `DJANGO_SECRET_KEY` environment variable in Heroku using the web interace or the [CLI](https://devcenter.heroku.com/articles/heroku-cli). If using the CLI, you can set a `SECRET_KEY` like so:
-
-    heroku config:set DJANGO_SECRET_KEY=changeme
-
-To learn more about Heroku, read [Deploying Python and Django Apps on Heroku](https://devcenter.heroku.com/articles/deploying-python).
-
-### Storing Wagtail Media Files on AWS S3
-
-If you have deployed the demo site to Heroku or via Docker, you may want to perform some additional setup. Heroku uses an
-[ephemeral filesystem](https://devcenter.heroku.com/articles/dynos#ephemeral-filesystem), and Docker-based hosting
-environments typically work in the same manner. In laymen's terms, this means that uploaded images will disappear at a
-minimum of once per day, and on each application deployment. To mitigate this, you can host your media on S3.
-
-This documentation assumes that you have an AWS account, an IAM user, and a properly configured S3 bucket. These topics
-are outside of the scope of this documentation; the following [blog post](https://wagtail.org/blog/amazon-s3-for-media-files/)
-will walk you through those steps.
-
-This demo site comes preconfigured with a production settings file that will enable S3 for uploaded media storage if
-`AWS_STORAGE_BUCKET_NAME` is defined in the shell environment. All you need to do is set the following environment
-variables. If using Heroku, you will first need to install and configure the [Heroku CLI](https://devcenter.heroku.com/articles/heroku-cli). Then, execute the following commands to set the aforementioned environment variables:
-
-    heroku config:set AWS_STORAGE_BUCKET_NAME=changeme
-    heroku config:set AWS_ACCESS_KEY_ID=changeme
-    heroku config:set AWS_SECRET_ACCESS_KEY=changeme
-
-Do not forget to replace the `changeme` with the actual values for your AWS account. If you're using a different hosting
-environment, set the same environment variables there using the method appropriate for your environment.
-
-Once Heroku restarts your application or your Docker container is refreshed, you should have persistent media storage!
-
-Running `./manage.py load_initial_data` will copy local images to S3, but if you set up S3 after you ran it the first
-time you might need to run it again.
-
 # Next steps
 
 Hopefully after you've experimented with the demo you'll want to create your own site. To do that you'll want to run the `wagtail start` command in your environment of choice. You can find more information in the [getting started Wagtail CMS docs](https://docs.wagtail.org/en/stable/getting_started/index.html).