Fix outdated info in datamodel about dicts (GH-9807)

Author: wimglenn

Doc/reference/datamodel.rst

@@ -1452,8 +1452,8 @@ Basic customization
       dict insertion, O(n^2) complexity.  See
       http://www.ocert.org/advisories/ocert-2011-003.html for details.
 
-      Changing hash values affects the iteration order of dicts, sets and
-      other mappings.  Python has never made guarantees about this ordering
+      Changing hash values affects the iteration order of sets.
+      Python has never made guarantees about this ordering
       (and it typically varies between 32-bit and 64-bit builds).
 
       See also :envvar:`PYTHONHASHSEED`.