Use --password-stdin

[snpdev]

For users using their own jumpbox, on the HOL #2 step:

docker login --username $ACR_USER --password $ACR_PWD $ACR_SERVER

... they may receive the following message:

WARNING! Using --password via the CLI is insecure. Use --password-stdin.

The solution is to use vi to write the password to a txt file (e.g. ~/acr-pw.txt) and then use this alternative login command:

 cat ~/acr-pw.txt | docker login $ACR_SERVER -u $ACR_USER --password-stdin

Is this deserving of a PR? Perhaps it's a bit out of scope.

[chzbrgr71]

This is probably out of scope and might only lead to confusion. Some things are good to leave in there and lead to questions and discussion.