Package pre-built sphinx docs with dune release tars

The default help provided by dune is not detailed enough.

It would be great if we could type dune help and this would open a browser window showing dune documentation. These would be the same docs you get by invoking make doc in dune source (essentially what you get at https://dune.readthedocs.io ).

We can't assume that people have sphinx installed on their local machine. So I'm not advocating that we build the docs when we install dune on a switch.

I am suggesting that we package up pre-built sphinx generated documentation into the opam tbz release files.

Precedent
For those who use the fish shell, if you type

$ help

It opens locally stored HTML documentation for the fish shell in your browser. (If you don't use fish, please install it momentarily to just try this out...)

Possible Issues
I built sphinx documentation and looked at it locally. Everything looks good.

However, it looks like there is a regression in the search feature on localhost. I get search results but I am not able to see the matching hits and their context. I understand that readthedocs provides full text search over and above the default sphinx browser search.

• Do you think this feature is useful?
• If so, would the dune team be interested in implementing it?
• If the feature is considered useful but the dune team does not have the time, I can volunteer to implement this feature but I would appreciate some general pointers on how to proceed...

Start with the dune help entry point and the make doc workflow described in the issue, then trace how opam tbz release files are assembled. Done means pre-built Sphinx HTML documentation is included in releases and dune help opens it locally; check the reported localhost search behavior as part of validation.