Mirrors the SUDO=/NO_SUDO=1 pattern from scripts/dev.sh so the script
works on hosts where the user isn't in the docker group (the default
on this dev box). Without this, 'docker info' fails immediately even
though 'docker login' (which needs no daemon socket) succeeds, and
publish.sh aborts before doing anything.
Reminder text updated to tell operators to 'sudo docker login' (or to
opt into rootless docker via NO_SUDO=1).
yiekheng
66737596b8