Add WSGIPassAuthorization to docs.

I haven't tried it, but it sounds like you need to enable wsgi to pass
the authorization header to Chishop. This is done in theapacheconfig
with:

```
   WSGIPassAuthorization On
```

Distutils and PyPI uses Basic Auth, and without this optionApache
will just swallow the header and handle it by itself.

that solved my problem, please consider to add this info somewhere in
docs.
