add brew installation instructions

[domoritz]

Checklist

• Used a personal fork of the feedstock to propose changes
• Bumped the build number (if the version is unchanged)
• Reset the build number to 0 (if the version changed)
• Re-rendered with the latest conda-smithy (Use the phrase @conda-forge-admin, please rerender in a comment in this PR for automated rerendering)
• Ensured the license file is being packaged.

[jakirkham]

Thanks Dominik! 😄

[domoritz]

Once Homebrew/homebrew-cask#97538 is merged, ARM should work out of the box.

I wonder whether it would be possible to automatically update the brew formula when there is a new release or whether you want to make it part of the release process. There is a command-line tool for making updates: https://github.com/Homebrew/homebrew-cask/blob/master/CONTRIBUTING.md#updating-a-cask.

[domoritz]

Just confirmed that brew install miniforge works out of the box on a MacBook with M1.

[hmaarrfk]

is it running everything through rosetta? or native?

[domoritz]

It's installing native versions of packages (e.g. Python) and runs natively.

See https://github.com/Homebrew/homebrew-cask/blob/34bc35b5f61a01cd3fdf36228ca9c0408be1d91a/Casks/miniforge.rb#L4 for the conditional that makes sure to download the right installer.