Internal documentation

[afandian]

Get documentation in a state where it contains all existing knowledge, is correct, and can support and be fully included in feature development. Remove doubt from the code.

Existing existing documentation may concern:

• Development
• Testing
• Deployment & Operations

Definition of done:

• One place for public docs, one place for development docs. Others removed.
• Data flows upstream and downstream of the REST API are documented, and product managers for those identified. This will include internal APIs and services.
• There are no outstanding TODOs, all have been removed and / or turned into issues.