add documentation for windows_container flag
add documentation for windows_container flag

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