Examples and best practices for numerous possible DAGs of Catalog, Collection, and Item

[philvarner]

In the text, we state that a Catalog can link to child Catalog, Collection, or Item objects and a Collection can link to child Collection or Item objects. However, we should also have:

• recommendations on when you would use each of these configurations
• references to different production catalogs that use these different configs, e.g., Astraea has a simple Catalog->Collection->Item model, with one Catalog for all data and each product (Landsat 8 L1TP, Sentinel-2 L2A) in a Collection
• JSON examples for several instances of these with a diagram to to show these relationships. E.g.,
  • (1) a simple Catalog -> Collection -> Item,
  • (2) Catalog -> (sub)Catalog -> Collection,
  • (3) Catalog -> Collection -> (sub)Collection -> Item,
  • (4) Collection -> Item,
  • (5) Catalog -> Item,
  • (6) Catalog -> {Item, Collection -> Item}

[cholmes]

Putting this for rc.3. I think it's ok if we just do this in how-to / tutorial documentation, but I could also see putting this in best practices.

[PowerChell]

Broader issue to be tackled (survey, improve best practices documentation, etc) to be orchestrated by Radiant Earth.