Document Hoed better

[ndmitchell]

Specifically there are no docs for:

data Config
class Observable a
observer :: Observable a => a -> Parent -> a
constrain :: Observable a => a -> a -> a
observe :: Observable a => String -> a -> a
data HoedOptions :: *
defaultHoedOptions :: HoedOptions

My checking script complains, which explains the Travis GHC 8.2 error.

[ndmitchell]

CC @pepeiborra

[pepeiborra]

So that was the reason !

Maybe the ticket should belong in the Hoed repo. Part of these are already addressed by my last PR, but it isn't merged yet.

[ndmitchell]

I've disabled the documentation check for debug temporarily