add missing packaging files

src/zope/PACKAGE.cfg

+# zope is a container package, so it really doesn't include much.
+
+<collection>
+
+  __init__.py
+  README.txt
+
+</collection>

src/zope/README.txt

+=====================
+Zope Project Packages
+=====================
+
+The ``zope`` package is a pure namespace package holding packages
+developed as part of the Zope 3 project.
+
+Generally, the immediate subpackages of the ``zope`` package should be
+useful and usable outside of the Zope application server.  Subpackages
+of the ``zope`` package should have minimal interdependencies,
+although most depend on ``zope.interface``.
+
+The one subpackage that's not usable outside the application server is
+the ``app`` subpackage, ``zope.app``, which *is* the application
+server.  Sub-packages of ``zope.app`` are not usable outside of the
+application server.  If there's something in ``zope.app`` you want to
+use elsewhere, let us know and we can talk about abstracting some of
+it up out of ``zope.app``.