Explicitly state that MacOS is not supported

Hi there,

I know it is not a very useful change for the project but it would be convenient if the project's readme stated clearly that MacOS is not supported (or that only Linux and Windows are supported).

For context: there are a few package managers that have level-zero as a package. Conan, for example.
Conan has a rather old version of level-zero and updating it stuck on the fact that macOS build in CI is failing.
The maintainer is reluctant to explicitly mark no support for macOS even thought MacOS build has not much purpose.
On the other hand one can understand the maintainer, cause the project doesn't articulate the lack of support for MacOS in any explicit way and even has some comments in code implying that developers had it in mind when the code was written.

Inizia dal README del progetto, che l’issue identifica come il punto che necessita di chiarimenti. Aggiungi una dichiarazione esplicita del fatto che macOS non è supportato, oppure che sono supportati solo Linux e Windows, e verifica che lo stato del supporto sia inequivocabile per i manutentori dei pacchetti.