Add first docs on how to setup dev environment, advances #12.

docs/dev/setup.rst

+Setting up the development environment
+======================================
+
+BiscuIT and all official apps use `Poetry`_ to manage virtualenvs and
+dependencies. You should make yourself a bit confortable with poetry
+by reading its documentation.
+
+Poetry makes a lot of stuff very easy, especially managing a virtual
+environment that contains BiscuIT and everything you need to run the
+framework and selected apps.
+
+
+Get the source tree
+-------------------
+
+To download BiscuIT and all officially bundled apps in their
+development version, use Git like so::
+
+  git clone --recurse-submodules https://edugit.org/Teckids/BiscuIT/BiscuIT-ng
+
+If you do not want to download the bundled apps, leave out the
+``--recurse-submodules`` option.
+
+
+Get Poetry
+----------
+
+Make sure to have Poetry installed like described in its
+documentation. Right now, we encourage using pip to install Poetry
+once system-wide (this will change once distributions pick up
+Poetry). On Debian, for example, this would be done with::
+
+  sudo apt install python3-pip
+  sudo pip3 install poetry
+
+You can use any other of the `Poetry installation methods`_.
+
+
+Install BiscuIT-ng in its own virtual environment
+-------------------------------------------------
+
+Poetry will automatically manage virtual environments per project, so
+installing BiscuIT is a matter of::
+
+  poetry install
+
+
+Running commands in the virtual environment
+-------------------------------------------
+
+To run commands in the virtual environment, use Poetry's ``run``
+command::
+
+  poetry run ./manage.py runserver
+
+.. _Poetry: https://poetry.eustace.io/
+.. _Poetry installation methods: https://poetry.eustace.io/docs/#installation

docs/index.rst

@@ -10,6 +10,7 @@ Welcome to BiscuIT's documentation!
    :maxdepth: 2
    :caption: Contents:
 
+   dev/setup
 
 
 Indices and tables