change docker.server to docker.service in kuryr-guide.rst
change docker.server to docker.service in kuryr-guide.rst

TrivialFix

Change-Id: I96adbc1c09601d4ea6e7a63978441f1bb35462ad

openstack/kolla,coolsvap/kolla,openstack/kolla,rahulunair/kolla,dardelean/kolla-ansible,coolsvap/kolla,GalenMa/kolla,mrangana/kolla,stackforge/kolla,dardelean/kolla-ansible,coolsvap/kolla,mrangana/kolla,stackforge/kolla,dardelean/kolla-ansible,intel-onp/kolla,stackforge/kolla,GalenMa/kolla,nihilifer/kolla,intel-onp/kolla,nihilifer/kolla,rahulunair/kolla