Exit more gracefully when downloading release #35
Description
When a user tries to download a version using semantics like this: zig 0.14.0, it downloads the release and then attempts to run the release without any arguments. This returns Zig's "expected command argument" error. It would probably make sense to assume the user meant to do this and exit gracefully.
I opened a pull request here #34 which simply exits the program. Other options might be better/more explicit like running Zig with the version flag to confirm what was downloaded, or the help flag to return the help menu without throwing an error.
This is only relevant during the initial download step, if the release is already installed it should function as it does now.