I think the tutorials in your docs are outdated. At least this one isn’t working:
It should be
$ docker build --tag quickstart-go .
$ docker-cloud build --tag quickstart-go .
And in general I get a lot of error messages and warnings following your tutorial on docker cloud.
EDIT: Here for example you reference the image as /my_image but it should be of course /quickstart-go . In general your tutorials could use a lot of clarification and improvement. It is hard to understand the differences between docker, docker cloud, docker engine, docker toolbox, docker whatever