Add qc developer guide to documentation

We should adapt Piot's developer guide for `qc` (as well as adding anything else relevant) and this to our docs for better discoverability.

Start by locating Piot's existing developer guide and the current documentation entry point for qc. Adapt the guide for this project, add any relevant qc material identified during review, and ensure the resulting documentation is discoverable from the existing docs.

Written by the indexing model from the issue text.