This is what I have in mind at the moment (but we should try to reduce the number of topics by merging some of them)

• Custom Encoding/Decoding (to Structs)
• Decoding from &str
• Default Decoding/Encoding #[deriving(Encodable,Decodable)]
• Encoding to String
• Error handling (DecoderError, ParserError, etc)
• Streaming (which is not documented)
• The Json intermediate struct
• ToJson
• How JSON types match to Rust types: null <-> None, [] <-> Vec, "" <-> String, Object <-> TreeMap<String, T>/HashMap<String, T>

Feedback is welcome!

Order-wise, this chapter should be after the "hashmap"/"treemap" chapters.

The structure of the chapter should look like this (some topics are still missing):

.
|-- `Json` -> The `Json` enum and its variants
|   |-- Decoding -> `json::from_str` + `BuilderError`
|   |-- `ToJson`` -> struct -> `Json`
|   `-- Stringify??? -> `Json` -> `String`
|-- `Decoder` -> `Json` -> `Decoder` -> `T` - where `T` = `Vec`, `String`, `HashMap`, etc
|-- `Decodable` -> `#[deriving(Decodable)]`
|   `-- Custom??? -> Manually implement `Decodable`
`-- `Encodable` -> `#[deriving(Encodable)]`, `str_encode`
    `-- Custom??? -> Manually implement `Encodable`

@vojtechkral is working on this