Remove the configure portion of extension docs

The docs themselves have little to do with configuration,
and mostly describe how to enable the extension.
Suggest removing the configuration part of the file rename.
Also motivating this change, is the fact that we are including
a doc that helps to configure the federation extension
(https://review.openstack.org/#/c/89220/).

Change-Id: I0fe845ac9bdfede330a7eb56fee6f971290789b3
Merge "Remove the configure portion of extension docs"