Properly document field referencing rules

[roblabla]

Most important are :

• Document properly what field referencing is (compareTo, count field, etc...)
• Specify how to go up the hierarchy with super
• Specify what datatype influence super
• etc...

[rom1504]

https://github.com/ProtoDef-io/ProtoDef/blob/master/schemas/definitions.json#L5 is the only place where it's documented atm
do we have super ?

[roblabla]

I am so confused about how everything works. According to https://github.com/ProtoDef-io/node-protodef/blob/master/src/utils.js#L1, getField, parses things like "../../some/field"

EDIT: Wait no. It actually does this : if it starts with a /, it goes back to the root context. Otherwise, it is relative, just like a normal path.

[rom1504]

Oh yeah we do handle .. which is super.

Ok yes that definitely needs documenting.