Add debugging/troubleshooting section to docs

[cc-a]

The development stack and interaction of drunc components is fairly complex. It would be a good idea to have a section in the docs for troubleshooting steps one can use to test different parts of the system.

This could cover:

• using drunc commandline tools to interact with different drunc components.
• checking Kafka messages are being sent.
• using some of the helper scripts included in the repo..