https://dmtn-030.lsst.io describes an architecture for pipelines.lsst.io with key topic types and sections:

• Processing contexts
• Frameworks
• Modules (that contain task and API documentation as well)

The aim of this ticket is to stub out this structure so that

1. The DM team understands the structure.
2. We have pages to begin pouring content into (initially from Doxygen).

The ticket won't cover putting content in all the stub pages.