Improvement to docker-compose

[nvtkaszpir]

Is your feature request related to a problem? Please describe. Looks like current out-of-the-box experience when using docker-compose is a bit lacking.

Describe the solution you'd like Improve docker-compose:

• add grafana config to auto-register prometheus as default datasource
• adjust grafana so that it loads predefined dashboard on start, for example the one from examples (it could be also improved in another PRs

I can create PR in about 7 days.

Comments?

[nvtkaszpir]

CC @Tomasz-Kluczkowski because I've seen you've been doing some prometheus/grafana work