Document all wit keywords: const, ...

[nuke-web3]

I see resource used in https://github.com/WebAssembly/WASI/blob/main/preview2/http/types.wit#L146 and other places, notably https://github.com/WebAssembly/wasi-http/blob/main/wit-0.3.0-draft/types.wit#L254-L339 is one that is intuitively exposes a collection of func() and I am guessing optionally a constructor(). WIP covers resource 😁

Some keywords mentioned in https://component-model.bytecodealliance.org/design/wit.html at this time are not covered in the book - I would expect all keywords would have a mention... but maybe I just have not found out yet that those are not user facing somehow and reserved for wasi internally or something? 😓

[itowlson]

Resources are in progress at #103