docs: document how to contribute to docs; r=sheehan

Differential Revision: https://phabricator.services.mozilla.com/D10405

--HG--
extra : moz-landing-system : lando

docs/devguide/docs.rst

@@ -0,0 +1,35 @@
+.. _devguide_docs:
+
+=============================
+Contributing to Documentation
+=============================
+
+Improvements to the documentation in this repository are very welcome!
+
+Building Documentation Locally
+==============================
+
+To build documentation locally, you will need a Python environment.
+
+Assuming you already have a copy of the source repository, run the
+following commands to activate the environment for building the docs::
+
+   $ ./create-environment docs
+   $ source venv/docs/bin/activate
+
+Then to build the docs::
+
+   $ make -C docs html
+
+You can then open docs/_build/html/index.html in your web browser to
+navigate the generated docs.
+
+Submitting Patches
+==================
+
+If you have a change to the docs that you would like to be incorporated,
+please follow the :ref:`regular contributing guide <devguide_contributing>`
+to learn how to submit patches.
+
+Commit messages for documentation-only changes should be prefixed with
+``docs:``.

docs/devguide/index.rst

@@ -11,6 +11,7 @@ come to the right place!
    :maxdepth: 2
 
    contributing
+   docs
    environment
    testing
    jenkins