Document `force_provider_authentication` not being effective when logging in with ssh public key authentication
It's currently not made clear that this option is uneffective when the user logs in with ssh with public key authentication.
We should note that at least in the section in the authd documentation, maybe also in the comment in the broker config file.
While at it, we might also want to document that authentication to use sudo is also affected by the force_provider_authentication option, so you can't even use sudo when the option is enabled and your internet connection isn't working.
Yeah, maybe we should mention that if only authd method can be supported when in SSH then the AuthenticationMethods sshd option should contain only keyboard-interactive.