Update docs for auth_token middleware config options
Update docs for auth_token middleware config options

The documentation for the auth_token middleware config options
was out of date.

Change-Id: I8d03d77c58c714375e1e5174962991aa3adc61af

alexpilotti/python-keystoneclient,jamielennox/python-keystoneclient,darren-wang/ksc,jamielennox/python-keystoneclient,alexpilotti/python-keystoneclient,sdpp/python-keystoneclient,ging/python-keystoneclient,ging/python-keystoneclient,darren-wang/ksc,Mercador/python-keystoneclient,magic0704/python-keystoneclient,klmitch/python-keystoneclient,magic0704/python-keystoneclient,klmitch/python-keystoneclient,Mercador/python-keystoneclient,sdpp/python-keystoneclient,jamielennox/python-keystoneclient