docs: move dev setup to docs site, fix docs header

website/docs/development/local-dev-environment.md

@@ -0,0 +1,42 @@
+---
+title: Setting up a local dev environment
+---
+
+## Backend
+
+To create a local development setup for passbook, you need the following:
+
+- Python 3.9
+- pipenv, which is used to manage dependencies, and can be installed with `pip install pipenv`
+- PostgreSQL (any recent version will do)
+- Redis (any recent version will do)
+
+For PostgreSQL and Redis, you can use the docker-compose file in `scripts/`. You can also use a native install, if you prefer.
+
+To configure passbook to use the local databases, create a file in the passbook directory called `local.env.yml`, with the following contents
+
+```yaml
+debug: true
+postgresql:
+  user: postgres
+
+log_level: debug
+```
+
+Afterwards, you can start passbook by running `./manage.py runserver`. Generally speaking, passbook is a Django application.
+
+Most functions and classes have type-hints and docstrings, so it is recommended to install a Python Type-checking Extension in your IDE to navigate around the code.
+
+## Frontend
+
+By default, no transpiled bundle of the frontend is included. To build the UI, you need Node 12 or newer.
+
+To build the UI, run these commands:
+
+```
+cd web/
+npm i
+npm run build
+```
+
+If you want to make changes to the UI, run `npm run watch` instead.