Fixed interface documentation typo.
Fixed interface documentation typo.

paulmey/packer,timsutton/packer,pecigonzalo/packer,grubernaut/packer,dave2/packer,mitchellh/packer,bryson/packer,tas50/packer,ricardclau/packer,timsutton/packer,hashicorp/packer,grubernaut/packer,dave2/packer,mitchellh/packer,rnaveiras/packer,paulmey/packer,tas50/packer,grubernaut/packer,timsutton/packer,mitchellh/packer,bryson/packer,ricardclau/packer,pecigonzalo/packer,rnaveiras/packer,bryson/packer,ricardclau/packer,timsutton/packer,hashicorp/packer,paulmey/packer,tas50/packer,mitchellh/packer,paulmey/packer,bryson/packer,dave2/packer,grubernaut/packer,paulmey/packer,ricardclau/packer,pecigonzalo/packer,hashicorp/packer,paulmey/packer,rnaveiras/packer,grubernaut/packer,tas50/packer,ricardclau/packer,dave2/packer,dave2/packer,rnaveiras/packer,bryson/packer,rnaveiras/packer,dave2/packer,grubernaut/packer,pecigonzalo/packer,timsutton/packer,hashicorp/packer,ricardclau/packer,timsutton/packer,tas50/packer,mitchellh/packer,bryson/packer,tas50/packer,rnaveiras/packer