Typo error in keystone/doc/source/configuration.rst.
Typo error in keystone/doc/source/configuration.rst.

Change-Id: I076d4679cd797db816b99e63053661515712302b

vivekdhayaal/keystone,rushiagr/keystone,vivekdhayaal/keystone,jonnary/keystone,openstack/keystone,savi-dev/keystone,takeshineshiro/keystone,ntt-sic/keystone,citrix-openstack-build/keystone,rodrigods/keystone,reeshupatel/demo,vivekdhayaal/keystone,ajayaa/keystone,klmitch/keystone,dstanek/keystone,ilay09/keystone,rajalokan/keystone,townbull/keystone-dtrust,promptworks/keystone,blueboxgroup/keystone,JioCloud/keystone,mahak/keystone,rodrigods/keystone,ajayaa/keystone,maestro-hybrid-cloud/keystone,blueboxgroup/keystone,nuxeh/keystone,MaheshIBM/keystone,derekchiang/keystone,rajalokan/keystone,cloudbau/keystone,ntt-sic/keystone,UTSA-ICS/keystone-kerberos,jamielennox/keystone,idjaw/keystone,openstack/keystone,cloudbau/keystone,idjaw/keystone,ging/keystone,openstack/keystone,himanshu-setia/keystone,mahak/keystone,rickerc/keystone_audit,cbrucks/Federated_Keystone,roopali8/keystone,ging/keystone,mahak/keystone,savi-dev/keystone,kwss/keystone,savi-dev/keystone,dims/keystone,kwss/keystone,cbrucks/Federated_Keystone,reeshupatel/demo,rickerc/keystone_audit,dstanek/keystone,derekchiang/keystone,jonnary/keystone,dsiddharth/access-keys,dsiddharth/access-keys,jumpstarter-io/keystone,townbull/keystone-dtrust,citrix-openstack-build/keystone,rajalokan/keystone,MaheshIBM/keystone,reeshupatel/demo,cernops/keystone,promptworks/keystone,rushiagr/keystone,maestro-hybrid-cloud/keystone,jamielennox/keystone,kwss/keystone,nuxeh/keystone,himanshu-setia/keystone,dstanek/keystone,nuxeh/keystone,klmitch/keystone,dsiddharth/access-keys,citrix-openstack-build/keystone,promptworks/keystone,jumpstarter-io/keystone,rickerc/keystone_audit,ilay09/keystone,derekchiang/keystone,ntt-sic/keystone,cbrucks/Federated_Keystone,rushiagr/keystone,roopali8/keystone,cernops/keystone,townbull/keystone-dtrust,JioCloud/keystone,takeshineshiro/keystone,dims/keystone,UTSA-ICS/keystone-kerberos,cloudbau/keystone,jumpstarter-io/keystone,ilay09/keystone