Docker completion for Zsh + prezto

docker.zsh

$ docker run<tab>
 -- no matches found --

$ curl -fLo ~/.zprezto/modules/completion/external/src/_docker https://raw.githubusercontent.com/docker/docker-ce/master/components/cli/contrib/completion/zsh/_docker

$ docker run<tab>
 -- images --
0a89c74fff6c  -- latest          in bradleybeddoes/docker-whale
 -- repositories --
bradleybeddoes/docker-whale

$ docker run bradleybeddoes/docker-whale:<tab>
$ docker run bradleybeddoes/docker-whale:latest
 _______________________________________
/ Everyone is a genius. It's just that  \
| some people are too stupid to realize |
\ it.                                   /
 ---------------------------------------
    \
     \
      \
                    ##        .
              ## ## ##       ==
           ## ## ## ##      ===
       /""""""""""""""""___/ ===
  ~~~ {~~ ~~~~ ~~~ ~~~~ ~~ ~ /  ===- ~~~
       \______ o          __/
        \    \        __/
          \____\______/