It seems that docker-compose isn’t included in the docker-engine package which is the one that the Docker project ship.
I expect then the docker-compose package you’re seeing is from Ubuntu or elsewhere.
Try running which docker-compose and apt-cache policy docker-compose
What do they output? That will tell us where it’s coming from.
In any case, you’ll need to remove the packaged version (by running apt-get remove --purge docker-compose), then install following the instructions for the latest release here:
I’ll file a bug to update the documentation for that. Windows and Mac versions of docker-engine do come with it bundled.