19929: Document schemas and their resources together in PySDK reference

19929: Document schemas and their resources together in PySDK reference

Now that all these classes are fully documented, outputting all the
schemas and then all the resources means there's a giant gap between
related classes. Provide nicer organization by sorting by methods,
preceding them with their related schemas. Refs #19929.

Arvados-DCO-1.1-Signed-off-by: Brett Smith <brett.smith@curii.com>