Update README
Update README

Updating the compilation steps for Opendaylight
demx8as6/CENTENNIAL,demx8as6/CENTENNIAL,OpenNetworkingFoundation/CENTENNIAL,demx8as6/CENTENNIAL,demx8as6/CENTENNIAL,OpenNetworkingFoundation/CENTENNIAL,demx8as6/CENTENNIAL,demx8as6/CENTENNIAL,OpenNetworkingFoundation/CENTENNIAL,demx8as6/CENTENNIAL,OpenNetworkingFoundation/CENTENNIAL