Link to Django's runserver options in dev docs

doc/development/setup.rst

@@ -83,6 +83,10 @@ As we did not implement an overall front page yet, you need to go directly to
 http://localhost:8000/control/ for the admin view or, if you imported the test
 data as suggested above, to the event page at http://localhost:8000/bigevents/2017/
 
+.. note:: If you want the development server to listen on a different interface or
+          port (for example because you develop on `pretixdroid`_), you can check
+          `Django's documentation`_ for more options.
+
 .. _`checksandtests`:
 
 Code checks and unit tests
@@ -148,3 +152,7 @@ To build the documentation, run the following command from the ``doc/`` director
     make html
 
 You will now find the generated documentation in the ``doc/_build/html/`` subdirectory.
+
+
+.. _Django's documentation: https://docs.djangoproject.com/en/1.11/ref/django-admin/#runserver
+.. _pretixdroid: https://github.com/pretix/pretixdroid