home-manager version switch --flake syntax

[dgolant]

In the readme, it says to run

home-manager switch --flake .#username@hostname

On my machine the above did not work. I may have the wrong version of home-manager (which then maybe could be explicitly called out?). The following DID work, though home-manager's opaque errors made it a bit hard to figure out.

❯ home-manager -- switch --flake .#username@hostname

I assume its a me problem, happy to open a PR against the readme, but I didn't want to propose a change that would break other users.