add release note for version 0.4.0
add release note for version 0.4.0

cmusatyalab/elijah-discovery-basic,cmusatyalab/elijah-discovery-basic,OpenEdgeComputing/elijah-discovery-basic,OpenEdgeComputing/elijah-discovery-basic,cmusatyalab/elijah-discovery-basic,OpenEdgeComputing/elijah-discovery-basic