Update usage strings to have meaningful types
Update usage strings to have meaningful types

flag.PrintDefaults() defaults to printing the variable's type name after
the flag. This changes it to print a type more meaningful to the user.

Previously the usage string looked like:

Usage of scan:
  -credentials file
    	OAuth 2.0 credentials file
    	Relative paths are taken as relative to -data.dir (default "client_secret.json")
  -data.dir string
    	Data directory (default ".")
  -http.addr string
    	HTTP address:port (default ":80")
  -https.addr string
    	HTTPS address:port (default ":443")
  -no-auth
    	Disable authentication
  -tls
    	Enable AutoTLS
  -tls.hostname string
    	(Optional) Hostname to restrict AutoTLS

After this change it looks like:

Usage of scan:
  -credentials file
    	OAuth 2.0 credentials file
    	Relative paths are taken as relative to -data.dir (default "client_secret.json")
  -data.dir path
    	Data directory path (default ".")
  -http.addr address
    	HTTP address:port (default ":80")
  -https.addr address
    	HTTPS address:port (default ":443")
  -no-auth
    	Disable authentication
  -tls
    	Enable AutoTLS
  -tls.hostname hostname
    	(Optional) Restrict AutoTLS to hostname

jamesog/scan,jamesog/scan,jamesog/scan