Update docs to support docker swarm

- again, copy from go

Closes #67
3 jobs for 67-docker-swarm in 1 minute and 35 seconds (queued for 2 seconds)
Status Name Job ID Coverage
  Test
passed whats-open-py2.7 #3645

00:01:29

passed whats-open-py3.5 #3646

00:01:34

passed whats-open-py3.6 #3647

00:01:35