The "docker inspect" command can inspect any type of object, which would
require all possible endpoints to be contacted. By default, we don't
provide completion, but if a `--type` is passed, we provide completion
for the given type.
For example, `docker inspect --type container` will complete container
names, `docker inspect --type volume` will complete volume names and
so on.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>