[crag] partition schedules migration guide
Summary: Title. I wish that there was a way to use partitioned config in tandem with config mapping, it would be a nice additional win if we could re-use a single partitioned config among multiple jobs.
Test Plan: adding unit tests
Reviewers: sandyryza, alangenfeld
Reviewed By: sandyryza
Differential Revision: https://dagster.phacility.com/D8979