Using `/var/run/docker.sock` as docker host is invalid, and causes
an error, so adding `unix://` to it.
In addition, we document the name of the context to go after the
options, so change the order in the examples.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
(cherry picked from commit 803b9071e7)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>