README.md: document Docker Volumes conversion
README.md: document Docker Volumes conversion

And add example.

dgonyeo/docker2aci,jsoriano/docker2aci,appc/docker2aci,dgonyeo/docker2aci,OMWAVE/docker2aci,vishvananda/docker2aci,jsoriano/docker2aci,vishvananda/docker2aci,jumpstarter-io/docker2aci,mclarkson/docker2aci,pquerna/docker2aci,ChengTiesheng/docker2aci,OMWAVE/docker2aci,appc/docker2aci,iaguis/docker2aci,jonboulle/docker2aci