Nearly 3 million people caught the launch of Aaron Sorkin’s “The Newsroom” on Sunday. About 2.1 million of that crowd watched the show’s 10p.m. unveiling. That audience puts “The Newsroom” in company with some of HBO’s most-watched recent premieres, including those of fantasy drama “Game of Thrones” (2.2 million) in April 2011 and vampire drama “True Blood” (1.4 million) in September of ’08.