Add the PyPA Code of Conduct

Author: dstufft

README.rst

@@ -8,3 +8,13 @@ virtualenv
    :target: http://travis-ci.org/pypa/virtualenv
 
 For documentation, see https://virtualenv.pypa.io/
+
+
+Code of Conduct
+---------------
+
+Everyone interacting in the virtualenv project's codebases, issue trackers,
+chat rooms, and mailing lists is expected to follow the
+`PyPA Code of Conduct`_.
+
+.. _PyPA Code of Conduct: https://www.pypa.io/en/latest/code-of-conduct/