explain how to run tests

doc/index.rst

@@ -11,6 +11,8 @@ Contents:
 .. toctree::
    :maxdepth: 2
 
+   tests
+
 
 .. autosummary::
     :toctree: _autosummary

doc/tests.rst

@@ -0,0 +1,7 @@
+Tests
+=====
+
+
+Run the tests like this:
+
+    >>> python3 -m tests.test_proto