Update python version support section in README

Author: Bjwebb

README.md

@@ -315,10 +315,11 @@ Python Version Support
 ----------------------
 
 This code supports Python 2.7 and Python 3.3 (and later). Python 3 is
-preferred, and any Python 2 specific bugs are currently treated as low
-priority.
+strongly preferred. Only servere Python 2 specific bugs will be fixed, see the
+[python2-wontfix](https://github.com/OpenDataServices/flatten-tool/issues?q=is%3Aissue+label%3Apython2-wontfix+is%3Aclosed)
+label on GitHub for known minor issues.
 
-Python 2.6 and earlier are not supported because our code makes use new
+Python 2.6 and earlier are not supported at all because our code makes use new
 language constructs introduced in Python 3 and 2.7. Python 3.2 (also 3.1 and
 3.0) is not supported, because one of the dependencies (openpyxl) does not
 support it.