add documentation for installing phive with homebrew

[sebastianheuer]

No description provided.

[localheinz]

Also see Homebrew/homebrew-core#39469.

[theseer]

Given that we keep marking phive as prerelease software and homebrew only wants "stable" releases, there's not that much we can do here currently.

I'm not convinced marking phive as stable would be justified already - but maybe I'm just too careful. Marking it stable just to be added to homebrew feels wrong as well.

That being said: I'm not even convinced we need special case for $environment. Phive comes as a phar which runs on any 7+ PHP Environment. Why would homebrew or any other distro require special installations? And on top of that: Isn't homebrew rather an alternative to phive when it comes to installing things?

[vukanac]

With brew installer, I would assume Phive would have more users and more recognition for development.

[theseer]

Certainly, but:

Given that we keep marking phive as prerelease software and homebrew only wants "stable" releases, there's not that much we can do here currently.