update services endpoint

[tomkralidis]

As per https://lists.osgeo.org/pipermail/pycsw-devel/2019-January/000805.html, the services in
http://demo.pycsw.org/services/csw?service=CSW&version=2.0.2&request=GetCapabilities are outdated/stale. Updated the endpoints and add a text file of an endpoint list that can be regenerated as required.

[jmckenna]

I agree that a text file explaining the endpoints would be very useful.