2.3.1

• bugfix: Register callback as root to avoid segfaults with mlfront_zip. Fixes https://gitlab.com/dkml/build-tools/MlFront/-/issues/3

Earlier

• Add .opam install instructions.
• Remote spec now includes a `kind field that can either be `std [`mirrors_clib []; ...] or `cload [`id "library_id"; `clib "..."; ...].