code: func (c *Client) UpdateServerGroup(updateServerGroup *ServerGroupOptions) (*ServerGroup, error) {
  	group := new(ServerGroup)
  	_, err := c.MakeApiRequest("PUT", "/1.0/server_groups/"+updateServerGroup.Id, updateServerGroup, &group)
  	if err != nil {
  		return nil, err
  	}
  	return group, nil
  }
docs: // UpdateServerGroup updates an existing server groups's attributes. Not all
  // attributes can be changed (such as Id).
  //
  // Specify the server group you want to update using the ServerGroupOptions Id
  // field.
  //
  // To change group memberships, use AddServersToServerGroup,
  // RemoveServersFromServerGroup and MoveServersToServerGroup.