Beta Release of MirageOS 4.0

[Thomas Gazagnaire <thomas@xxxxxxxxxxxxxx>]

On behalf of the Mirage team, I am delighted to announce the beta release of 
MirageOS 4.0!

The beta of the MirageOS 4.00 release contains:
- mirage.4.0.0~beta: the CLI tool;
- ocaml-freestanding.0.7.0: a libc-free OCaml runtime;
- and solo5.0.7.0: a cross-compiler for OCaml.

They are all available in opam by using:

    $ opam install 'mirage>=4.0'

Note: you need to explicitly add the ‘mirage>=4.0' version here, otherwise opam 
will select the latest 3.* stable release. For a good experience, check that at 
least version 4.0.0~beta3 is installed.

Your feedback on this beta release is very much appreciated.  Issues are very 
welcome on the mirage/mirage GH bug-tracker, or come find us on Matrix in the 
MirageOS channel: #mirageos:matrix.org.

You can see the full feature list on https://mirage.io/docs/mirage-4 and on the 
release post: https://mirage.io/blog/announcing-mirage-40-beta-release

Best,
Thomas