Update macOS system requirements to include Sequoia (15.x), the latest
major version.
Release Notes:
- N/A
Co-authored-by: Marshall Bowers <elliott.codes@gmail.com>
This PR updates the system requirements in the docs to note that Linux
and Windows can be built from source.
This matches the messaging we have in place on the [download
page](https://zed.dev/download).
Release Notes:
- N/A