docs(samples): add processing samples for each processor category

[mattcarrollcode]

This is an issue to add samples to cover each category of Document AI's API processing responses:

• OCR
• form leaving
• quality
• splitter
• specialized

Currently only the form processor response is covered but only includes generic information on how to parse paragraphs. Each of these samples should cover aspects that are unique to the category
and general information that most or all developer will need to know how to parse and use.

This will give developers a starting point for each processor type that can be quickly and easily adapted to their use case.