Fix RST in configuration.rst
Fix RST in configuration.rst

Fix minor RST issue from before file was converted.

Change-Id: Ie16ceace9c17e98010e068641ce60ba9a365ede0

dtroyer/devstack,avvocatodemarchis/devstack,samgoon/devstack,richliu/devstack,noironetworks/devstack,samgoon/devstack,dtroyer/devstack,Mahito/devstack,dirkmueller/devstack,bswartz/devstack,thomasem/devstack,varunarya10/devstack,Mahito/devstack,bigswitch/devstack,richliu/devstack,thomasem/devstack,dirkmueller/devstack,group-policy/devstack,bswartz/devstack,openstack-dev/devstack,noironetworks/devstack,bigswitch/devstack,varunarya10/devstack,avvocatodemarchis/devstack,mssumanth/devstack,nawawi/openstack,nawawi/openstack,mssumanth/devstack,prithivm/branch01,prithivm/branch01,openstack-dev/devstack,group-policy/devstack