Documentation: Provide usage examples in non-trivial ways

[seanmay]

Rather than just writing examples that show JSON which completely matches the expected internal types of the closed system, also write types that show separate interfaces for the internal type, and the expected system input ("Is this data sufficient to pass to a constructor for my type?").

On top of that, show how if you receive superset god-objects, with all members nullable, you should validate against algebraic types which are the expected potential unions that could have been derived from that god object. "Is the input blob sufficient to make an A? Make an A. Is it sufficient to make a B? Make a B."