Added py3kwarning to the documentation of the sys module.
diff --git a/Doc/library/sys.rst b/Doc/library/sys.rst
index f9853e9..f254003 100644
--- a/Doc/library/sys.rst
+++ b/Doc/library/sys.rst
@@ -457,6 +457,12 @@
implement a dynamic prompt.
+.. data:: py3kwarning
+
+ Bool containing the status of the Python 3.0 warning flag. It's ``True``
+ when Python is started with the -3 option.
+
+
.. function:: setcheckinterval(interval)
Set the interpreter's "check interval". This integer value determines how often