Add some tips for IntelliJ IDEA to Docker Tutorial

[Mateusz512]

Docker Tutorial can be enriched with some tips on how to handle Docker with IntelliJ:

1. How to Start/Stop Docker containers
2. How to chain gradle build with starting the container
3. Creating one build configuration for Stop->Rebuild->Start

[malaskowski]

I don't think that's part of knowledge that Knot.x tutorials should cover. Some general tips are ok, but a detailed guide on how to setup IntelliJ and Docker can be e.g. referenced from somewhere else so that it will not require updating and maintaining in the future on knotx.io.