Odoc is not valid for OCaml 4.04.
There was a new release of odoc with 4.04 support yesterday. I'm not sure it's made its way on to opam yet.
In addition, Odoc does not appear to be documented
Yeah, I wouldn't say that odoc is ready to be used directly by users as it's not yet documented and the interface is still being finalised. However, there is support for it in jbuilder and odig which are both documented and ready to use.
For example, these pages are generated using odig:
and these are generated using jbuillder:
is Odoc intended to become a standard for generating OCaml documentation
And what are the best ways to contribute (eg by creating a layout?)
Probably by trying it out via odig or jbuilder and reporting issues on the github repo: