JSON Docu

[SchlenkR]

Better docu for working with JSON

• Explain some JSON extensions for SystemTextJson (like GetList() )
• The JSON Api can be shadowed for Newtonsoft + FSHarp.Data
• Working with dynamic JSON with all 3 JSON APIs

Aside from docu: The API is a little bit verbose, and we could think about introducing some useful daily-work shortcuts, like:

• json.GetList("children"), etc.