Since 1.9, Docker Content Trust Offline key has been renamed to
Root key and the Tagging key has been renamed to Repository key.
The corresponding environment variables
`DOCKER_CONTENT_TRUST_OFFLINE_PASSPHRASE`
`DOCKER_CONTENT_TRUST_TAGGING_PASSPHRASE`
have also been deprecated and renamed to
`DOCKER_CONTENT_TRUST_ROOT_PASSPHRASE`
`DOCKER_CONTENT_TRUST_REPOSITORY_PASSPHRASE`
This fix removed the deprecated ENV passphrase variables for
1.12 and updated the docs.
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>
Upstream-commit: e1242ed726
Component: cli
7e1b46c8ff