fix typo in README
fix typo in README

cmusatyalab/elijah-openstack,OpenEdgeComputing/elijah-openstack,cmusatyalab/elijah-openstack,cmusatyalab/elijah-openstack,OpenEdgeComputing/elijah-openstack,OpenEdgeComputing/elijah-openstack,cmusatyalab/elijah-openstack,OpenEdgeComputing/elijah-openstack