Janet Jackson is set to make an appearance at the Grammy Hall of Fame Gala, while Erykah Badu has been added as a performer to the already announced lineup. For the event, taking place on May 8 at Los Angeles’ Beverly Hilton, Jackson will make a special appearance to celebrate the induction of her album “Rhythm Nation 1984” into the Grammy Hall of Fame. Badu, meanwhile, will join George Clinton and Funkadelic guitarist Blackbyrd McKnight in a tribute to Funkadelic’s “Maggot Brain,” which is also among the 14 albums and songs being inducted into the Hall of Fame this year.…