docs(readme): add testing section

docs/README.rst

@@ -60,3 +60,48 @@ This state manages the file ``keepalived.conf`` under ``/etc/keepalived`` (templ
 ``keepalived.service``
 ----------------------
 This state ensures that keepalived service is running.
+
+Testing
+-------
+
+Linux testing is done with ``kitchen-salt``.
+
+Requirements
+^^^^^^^^^^^^
+
+* Ruby
+* Docker
+
+.. code-block:: bash
+
+   $ gem install bundler
+   $ bundle install
+   $ bin/kitchen test [platform]
+
+Where ``[platform]`` is the platform name defined in ``kitchen.yml``,
+e.g. ``debian-9-2019-2-py3``.
+
+``bin/kitchen converge``
+^^^^^^^^^^^^^^^^^^^^^^^^
+
+Creates the docker instance and runs the ``keepalived`` main state, ready for testing.
+
+``bin/kitchen verify``
+^^^^^^^^^^^^^^^^^^^^^^
+
+Runs the ``inspec`` tests on the actual instance.
+
+``bin/kitchen destroy``
+^^^^^^^^^^^^^^^^^^^^^^^
+
+Removes the docker instance.
+
+``bin/kitchen test``
+^^^^^^^^^^^^^^^^^^^^
+
+Runs all of the stages above in one go: i.e. ``destroy`` + ``converge`` + ``verify`` + ``destroy``.
+
+``bin/kitchen login``
+^^^^^^^^^^^^^^^^^^^^^
+
+Gives you SSH access to the instance for manual testing.