Over a few sessions, @papiris:data.coop and I pooled our knowledge and experience into [this pad](https://pad.data.coop/SCAk4RQhRBy84SylWQehIQ?view). This commit creates a How-To Guide, describing what we know so far about multinode setups. Meaning: 1 or more manager node, with 1 or more worker nodes in a docker swarm.