Demote warnings to notices where appropriate, following the goal that as few "red box" warnings
should clutter the docs as possible.  Part 1: stuff that gets merged to Py3k.
diff --git a/Doc/reference/executionmodel.rst b/Doc/reference/executionmodel.rst
index 05f8b92..9690a93 100644
--- a/Doc/reference/executionmodel.rst
+++ b/Doc/reference/executionmodel.rst
@@ -231,7 +231,7 @@
 :keyword:`except` clause is selected by object identity.  An arbitrary value can
 be raised along with the identifying string which can be passed to the handler.
 
-.. warning::
+.. note::
 
    Messages to exceptions are not part of the Python API.  Their contents may
    change from one version of Python to the next without warning and should not be