dune-release 2.1.0 generates broken documentation links

[talex5]

I just used dune-release 2.1.0 to publish a new package. It submitted a PR to opam-repository saying:

Documentation: https://talex5.github.io/libdrm-ocaml/

However, this link did not work. Looking at dune-release's changelog, it seems that documentation support is now disabled (I had to switch back to dune-release 2.0 and do dune-release publish doc to fix it).

Would be good to either allow publishing docs again, or at least stop publishing broken links.

(also, does this mean that all existing projects will have their documentation stop updating once they switch to 2.1?)