Recommend version 1.8.0 or later of six.

Signed-off-by: Daira Hopwood <[email protected]>

Author: daira

README.rst

@@ -16,10 +16,11 @@ single file::
     python-modernize -w example.py
 
 It does not guarantee, but it attempts to spit out a codebase compatible
-with Python 2.6+ or Python 3.  The code that it generates has a runtime
+with Python 2.6+ or Python 3. The code that it generates has a runtime
 dependency on `six <https://pypi.python.org/pypi/six>`_, unless the
-``--no-six`` option is used.  Some of the fixers output code that is not
-compatible with Python 2.5 or lower.
+``--no-six`` option is used. Version 1.8.0 or later of ``six`` is
+recommended. Some of the fixers output code that is not compatible with
+Python 2.5 or lower.
 
 See the ``LICENSE`` file for the license of ``python-modernize``.
 Using this tool does not affect licensing of the modernized code.