Make clear the status of the repo in README.md

Author: jeff5

README.md

@@ -1,22 +1,23 @@
-Jython: Python for the Java Platform
+This is not where Jython 3 is developing.
 
-Welcome to Jython 3.5!
+The latest version of Jython remains 2.7.x
+(see [Jython](https://github.com/jython/jython) for that).
+A Jython 3.x should appear there,
+but exploratory work towards it is not stable at the time of writing.
+Please watch the jython-dev mailing list for developements.
 
-This repo is in the very early stages of development of a release of
-Jython 3.5. Planned goals are language and runtime compatibility with
+This repo represents an attempt made in 2016 to implement a Jython 3.5,
+that is, with language and runtime compatibility with
 CPython 3.5, along with continued substantial support of the Python
 ecosystem.
+It is a sandbox for that venture.
+This code having branched from an early 2.7,
+the architecture is that of Jython 2,
+without taking advantage of the (then fairly new) dynamic language support.
+It has not been updated with subsequent bug-fixes made on Jython 2.7,
+and there is no plan to to do so.
 
 Please see ACKNOWLEDGMENTS for details about Jython's copyright,
 license, contributors, and mailing lists; and NEWS for detailed
 release notes, including bugs fixed, backwards breaking changes, and
 new features.
-
-
-TODO:
-
-1. Subclass PyString to BaseBytes class, so that it can share most behaviour with
-bytearray, rename to PyBytes
-
-2. Replace most occurrance of PyString with PyUnicode, which are used as string
-before.