Add info about generating documentation to readme

README.rst

@@ -99,6 +99,21 @@ can use `Tox <https://testrun.org/tox/latest/>`_:
     $ pip install tox
     $ tox
 
+*Documentation* consists of both a manually compiled user guide (under
+``docs/user``) and a reference guide generated from the docstrings using
+Sphinx autodoc with the napoleon extension. Documentation is built automatically
+on `ReadTheDocs`_ after each commit. To build documentation locally for testing:
+
+.. code-block:: console
+
+  $ cd docs
+  $ make html
+
+When writing docstrings, try to adher to the `Google style`_.
+
+.. _Google style: https://sphinxcontrib-napoleon.readthedocs.io/en/latest/example_google.html
+.. _ReadTheDocs: https://mwclient.readthedocs.io/
+
 Implementation notes
 --------------------