Create Dockerfile about server

[ricardobalk]

As can be seen in 247321f, the Dockerfile to build the map interface has been added. Will work on the Dockerfile for the API back-end soon. Might need something like docker-compose to combine the two and let them execute in the right order, because when want to use both the (Go-based) API back-end and the (Vue based) map interface, you'd need to build the map interface first and then run the back-end API.

How that works? Well, yarn run build usually builds the map interface and places the result in web/dist, and if web/dist exists, the Go server will serve that directory when visiting /. 🎉 added that in c8f0ac7

Anyways — the most practical thing would be to have a docker compose -d up or something similar that takes care of it. 😉