Configuration instructions don't provide enough clarity to get started

Problem

The Configuration section of our README is pretty sparse.

Customer:

[...] I wondered if we can run a custom version of this with handpicked plugins or is using the one provided by Gitlab the best version?

GitLab SA:

The customer and I have read our documentation on Code Quality, including the Code Quality yml file in the pub repo. I believe the short answer to his question is "yes, you can run your own custom scan definition", but - if that is the case, do they need to create/run a different Code Climate image, or can they simply create their own .codeclimate.yml and reference it instead of our default?

Although the contents of the configuration file itself are largely documented by CodeClimate, I don't think we provide enough clarity on how to use configuration files with CodeQuality and CodeClimate in our DinD CI setup.

Proposal

We should have a Getting Started section to walk people through using CodeQuality and setting up configuration to modify one of the project defaults, so it's clear and obvious where they should be making modifications.