Add that we support volumes_from
Add that we support volumes_from

Adds a note to the conversion doc that we support volumes_from.

Closes https://github.com/kubernetes-incubator/kompose/issues/476

procrypt/kompose,kubernetes/kompose,gitlawr/kompose,kubernetes/kompose,skippbox/kompose,ashetty1/kompose,cdrage/kompose,ashetty1/kompose,surajnarwade/kompose,surajnarwade/kompose,cdrage/kompose,skippbox/kompose,rupalibehera/kompose,procrypt/kompose,containscafeine/kompose,rupalibehera/kompose,ashetty1/kompose,procrypt/kompose,skippbox/kompose,kadel/kompose,containscafeine/kompose,kadel/kompose,gitlawr/kompose,rupalibehera/kompose,gitlawr/kompose,surajnarwade/kompose,containscafeine/kompose