Merge from 3.1: Issue #13703: add a way to randomize the hash values of basic types (str, bytes, datetime)
in order to make algorithmic complexity attacks on (e.g.) web apps much more complicated.

The environment variable PYTHONHASHSEED and the new command line flag -R control this
behavior.
diff --git a/Doc/library/sys.rst b/Doc/library/sys.rst
index d611acf..063e0a5 100644
--- a/Doc/library/sys.rst
+++ b/Doc/library/sys.rst
@@ -253,11 +253,15 @@
    :const:`verbose`              :option:`-v`
    :const:`bytes_warning`        :option:`-b`
    :const:`quiet`                :option:`-q`
+   :const:`hash_randomization`   :option:`-R`
    ============================= =============================
 
    .. versionchanged:: 3.2
       Added ``quiet`` attribute for the new :option:`-q` flag.
 
+   .. versionadded:: 3.2.3
+      The ``hash_randomization`` attribute.
+
 
 .. data:: float_info