[The docs](http://www.scala-sbt.org/sbt-native-packager/GettingStartedServers/MyFirstProject.html) say:

> 
> To build an image and store it in the local Docker server, use
> 
> 
> `docker:publishLocal`
> 
> 
> 

I'm just getting started with Docker and am not familiar with the concept of a "local Docker server". What is that and where should I look for the output of `docker:publishLocal`?