Link serialization specs to the conceptual model

[justincy]

It would be helpful if, in the serialization specs, each data type had a link the the data type's description in the conceptual model.

I particularly want this for a client library that uses the JSON serialization format. I want to link to the serialization format because it describes the properties and data types but the conceptual model does a better job of detailing restrictions and linking to enumerations.

I'm sure I'll eventually send a PR for JSON.