[Feature] Improve documentation for database types and how they are generated and documented.

What is the motivation for your feature request? Please describe what you want to use it for.

The process of adding new compound/complex data types to the database backends, for use by archetype developers, is arcane and poorly documented. The documentation does provide a list of available database types, but little about how to add new ones.

Describe the feature you'd like.

Add a page to the archetype developers guide that descibes:

1. how to add new data types
2. the various ways those data types are automatically processed and why

Describe alternatives you've considered.

The alternative is that developers need to do a forensic code study to figure out what's going on (or ask an AI agent to help).

Additional context.

This may be a good task for pair-programming since the complexity of these processes may be understood more easily by multiple people sharing perspectives.

How can this issue be closed?

Add a page to the documentation that covers these topics.