Minor doc updates, ensure README is in final tarball.

MANIFEST.in

@@ -1,3 +1,4 b''
+include README.rst
 include ipython.py
 include setup2.py
 include setup3.py

README.rst

@@ -5,11 +5,11 b''
 Overview
 ========
 
-Welcome to IPython. Our full documentation, including PDF versions of our
-manual, is available on `our website <http://ipython.org/documentation.html>`_;
-if you downloaded a built source distribution the ``docs/html`` directory
-contains an HTML version of the manual.  The ``docs/source`` directory contains
-the plaintext version of these manuals.
+Welcome to IPython.  Our full documentation is available on `our website
+<http://ipython.org/documentation.html>`_; if you downloaded a built source
+distribution the ``docs/source`` directory contains the plaintext version of
+these manuals.  If you have Sphinx installed, you can build them by typing
+``make html`` for local browsing.
 
 
 Dependencies and supported Python versions