Preauthkeys expire help message incomplete

[0xcd0e]

Tested on v0.10.2
The help message for the preauthkeys expire command does not include information about how to specify which key to expire:

# headscale preauthkeys -n testns expire --help
Expire a preauthkey

Usage:
  headscale preauthkeys expire [flags]

Flags:
  -h, --help   help for expire

Global Flags:
  -n, --namespace string   Namespace
  -o, --output string      Output format. Empty for human-readable, 'json' or 'json-line'

Usage should probably be:

Usage:
  headscale preauthkeys expire KEY [flags]