Add bash completion for `dockerd --ip6tables`
Add bash completion for `dockerd --ip6tables`

Signed-off-by: Harald Albers <64b2b6d12bfe4baae7dad3d018f8cbf6b0e7a044@albersweb.de>

docker/cli,thaJeztah/cli,cpuguy83/cli,docker/cli,thaJeztah/cli,cpuguy83/cli