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/c-api/intro.rst b/Doc/c-api/intro.rst
index e8a3fc4..c56000e 100644
--- a/Doc/c-api/intro.rst
+++ b/Doc/c-api/intro.rst
@@ -44,7 +44,7 @@
 ``<string.h>``, ``<errno.h>``, ``<limits.h>``, and ``<stdlib.h>`` (if
 available).
 
-.. warning::
+.. note::
 
    Since Python may define some pre-processor definitions which affect the standard
    headers on some systems, you *must* include :file:`Python.h` before any standard