Update: This column has been updated to correct the title of the film, which was originally misspelled.The documentary “RBG,” by filmmakers Julie Cohen and Betsy West, is a cinematic coming-out party for the Brooklyn-born, bantamweight Supreme Court justice, Ruth Bader Ginsburg — known by masses of adoring millennials as the Notorious R.B.G. The nickname is a play on the nom de rap of the corpulent “gangster” rapper, the late Notorious B.I.G., who was revered for the speed and ferocity of his …