Added note about dropping Python 2.6 (and possibly 3.3) support.

sybrenstuvel · sybrenstuvel · commit b57360048cb9 · 2016-03-17T16:58:23.000+01:00
diff --git a/README.md b/README.md
@@ -42,3 +42,5 @@ Those modules are marked as deprecated in version 3.4.
 
 Furthermore, in 4.0 the I/O functions will be streamlined to always work with bytes on all
 supported versions of Python.
+
+Version 4.0 will drop support for Python 2.6, and possibly for Python 3.3.
