Add docker-compose instructions

[jtpdowns]

If dotmotif were to be deployed in a Docker container, the default no-Neo4j-instance behavior would be to try to launch another container inside of the container. It would be good to describe the required steps to orchestrate an application container with a Neo4j container using docker-compose, which would allow you to network the two together and avoid the container-in-container problem.

[j6k4m8]

Big sigh of zero-github-issue relief: This is finally documented and explained in detail in the wiki.

And, incidentally: The pain-threshold for using the Neo4j executor is now way higher, since the GrandIsoExecutor bites way into the range of graph-sizes for which it used to make sense to switch to a graph database.

Woo! 🎉