Noting platform support in README

[jollygreenlaser]

If your project doesn't use any of the things listed under "Not yet supported", it should work fine. If not please open an issue.

M1/M2 macs are not supported. It's actually kind of unclear which platforms are supported, if any, beyond the Linux and x86_64 macOS that are noted as having nightly binaries.

It would be nice to have platform support explicitly noted so users can determine whether to attempt an install.

Related: #1248

[bjorn3]

Done

[jollygreenlaser]

Beautiful thank you!