Add new var for docker storage backend
Add new var for docker storage backend

datascienceinc/mantl,mantl/mantl,phnmnl/mantl,bitium/mantl,ContainerSolutions/microservices-infrastructure,CiscoCloud/mantl,sehqlr/mantl,mantl/mantl,bitium/mantl,CiscoCloud/mantl,ContainerSolutions/microservices-infrastructure,CiscoCloud/microservices-infrastructure,abn/microservices-infrastructure,KaGeN101/mantl,phnmnl/mantl,CiscoCloud/microservices-infrastructure,sehqlr/mantl,datascienceinc/mantl,abn/microservices-infrastructure,KaGeN101/mantl,abn/microservices-infrastructure