Clarify whether pythonhosted.org should be used

This PR addresses the question raised in issue #108 about whether pythonhosted.org should be used.  The wording on PyPI can lead packagers to think that pythonhosted.org is the "new way."

That's not quite true. Using pythonhosted.org has the advantage of supporting arbitrary docs generation systems (e.g. Dexy) and allowing a project's hosting presence to be entirely self-contained (i.e. depending solely on PyPI). It's not going anywhere, and will continue to be a fully supported model for docs deployment.

The advantage a service like RTFD offers is that it offers as low a barrier to entry to live docs publication that I am aware of, especially in combination with online editing and pull requests in a service like GitHub or BitBucket.