Remove reference to `config: version` option
Remove reference to `config: version` option

That doesn't actually do anything, so it shouldn't be listed in the docs.
pagodabox/nanobox-docker-mongodb,nanobox-io/nanobox-docker-mongodb,pagodabox/nanobox-docker-mongodb,pagodabox/nanobox-docker-mongodb,pagodabox/nanobox-docker-mongodb