code: func (i *TeleInstance) AddUser(username string, mappings []string) *User {
  	log.Infof("teleInstance.AddUser(%v) mapped to %v", username, mappings)
  	if mappings == nil {
  		mappings = make([]string, 0)
  	}
  	user := &User{
  		Username:      username,
  		AllowedLogins: mappings,
  	}
  	i.Secrets.Users[username] = user
  	return user
  }
docs: // Adds a new user into i Teleport instance. 'mappings' is a comma-separated
  // list of OS users