UK telecom giant BT Group plc on Monday appointed Indian billionaire Sunil Bharti Mittal and a Bharti Airtel Ltd. executive on its board.Mittal and Gopal Vittal, vice chairman and managing director of Bharti Airtel, will join the board of BT Group as non-independent non-executive directors, the company said in a statement.They will join the board as per the terms of a deal signed last year through which a Bharti Enterprises Ltd. subsidiary acquired a 24.5% stake in BT Group for an estimated $4 billion.Mitta ...