Move client config file logic, docs

cmd/subscribe_unix.go

@@ -12,7 +12,3 @@ or ~/.config/ntfy/client.yml for all other users.`
 var (
 	scriptLauncher = []string{"sh", "-c"}
 )
-
-func defaultClientConfigFile() (string, error) {
-	return defaultClientConfigFileUnix()
-}