Version-mark the dict order issue

Dictionary iteration order has been a solved problem since Python 3.6. Since this package supports as far back as 3.3, this could still be a problem, but only for people who are using older versions of Python. Clarifying the language to show this distinction.

README.rst

@@ -36,8 +36,8 @@ Problems & solutions
   that can be used as mapper instead of ``dict``. See the example section for details.
 
 - By default de-serialization will return a ``dict``, which doesn't preserve nor guarantee
-  key order due to `hash randomization`_. If key order is important then
-  I suggest using ``collections.OrderedDict``, or ``vdf.VDFDict``.
+  key order on Python versions prior to 3.6, due to `hash randomization`_. If key order is
+  important on old Pythons, I suggest using ``collections.OrderedDict``, or ``vdf.VDFDict``.
 
 Example usage
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