Document that you should use the hazmat directive
diff --git a/docs/contributing.rst b/docs/contributing.rst
index 6a76c70..e1475b8 100644
--- a/docs/contributing.rst
+++ b/docs/contributing.rst
@@ -117,10 +117,17 @@
So, specifically:
-- Always use three double quotes.
-- Put the three double quotes on their own line.
-- No blank line at the end.
-- Use Sphinx parameter/attribute documentation `syntax`_.
+* Always use three double quotes.
+* Put the three double quotes on their own line.
+* No blank line at the end.
+* Use Sphinx parameter/attribute documentation `syntax`_.
+
+When documenting a new module in the ``hazmat`` package, its documentation
+should begin with the "Hazardous Materials" warning:
+
+.. code-block:: rest
+
+ .. hazmat::
Development Environment
-----------------------