docs v2: Auth header API

[manzt]

from the prior docs

Authorization
-------------

If loading tiles from a secured server, the ``auth_token`` parameter takes the
string that will be used as the Authorization header on all tile requests sent
out by HiGlass:

.. code-block:: python

  (d,s,v) = higlass.display(views, auth_token='JWT DEADBEEF')

[manzt]

We don't currently have this API. This is really more something for the renderer and not the core schema API.