terms update: FQIN must include a tag

change: A fully qualified image name must include a tag.

Recommitting changes for PR: https://github.com/dotcloud/docker/pull/5145
since SvenDowideit suggested I would need to sign my commit for it to be accepted.

Docker-DCO-1.1-Signed-off-by: Justin Simonelis <justin.p.simonelis@gmail.com> (github: jsimonelis)