Change "services" to "service"
Change "services" to "service"

Because project name is service in Installation Guides[1],
It is better not to give reference of this name in installation
operation Documentation file.

[1]https://github.com/openstack/keystone/blob/master/doc/source/install/common/keystone-users.inc

Change-Id: Ib51341d023907b392acbdacd47bd1b3027b721a1

noironetworks/heat,openstack/heat,openstack/heat,noironetworks/heat