update RST for readme so pypi looks pretty
update RST for readme so pypi looks pretty

Navigating to https://pypi.python.org/pypi/os-client-config results
in seeing the raw RST content of the readme file. This is likely
caused by minor RST warnings, but pypi gives up and shows it raw.

Change-Id: Ia2d6202ade5282d9aeae9bb948175aae2aa264cd

dtroyer/python-openstacksdk,openstack/os-client-config,openstack/python-openstacksdk,openstack/python-openstacksdk,stackforge/python-openstacksdk,dtroyer/os-client-config,switch-ch/os-client-config,stackforge/python-openstacksdk,dtroyer/python-openstacksdk