The upstream tarball is missing some files, including the docs/ directory.  So
for now, just use the online documentation:

    http://pex.readthedocs.org/en/latest/

As soon as this upstream issue is resolved, I'll put the docs in the
python-pex-doc package:

    https://github.com/pantsbuild/pex/issues/51

 -- Barry Warsaw <barry@debian.org>, Thu, 19 Feb 2015 13:58:21 -0500
