Overhaul CI/CD and Deployment Documentation

[SorenSpicknall]

User story / feature request

As a maintainer of data infrastructure and deployed services, I want to know which pieces of our infrastructure employ fully automated deploys upon merge, which don't, and how the testing and deployment process works for each.

Acceptance Criteria

Improved build/test/deploy documentation for pieces of the data-infra repo that have corresponding CI/CD build tasks, as well as any deployed services not covered by our existing CI/CD pipelines.

Notes

Example offerings include Jupyterhub, the warehouse Docker image, and Composer/Airflow. This Issue will likely spawn several PRs, rather than being closed by a one-time bundle of documentation.