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/library/marshal.rst b/Doc/library/marshal.rst
index a9d6ea8..84fb138 100644
--- a/Doc/library/marshal.rst
+++ b/Doc/library/marshal.rst
@@ -85,7 +85,7 @@
    file must be an open file object opened in binary mode (``'rb'`` or
    ``'r+b'``).
 
-   .. warning::
+   .. note::
 
       If an object containing an unsupported type was marshalled with :func:`dump`,
       :func:`load` will substitute ``None`` for the unmarshallable type.