NEW YORK — Determined to keep him at 30 Rock, the newly married NBC Universal said Wednesday it has signed outgoing evening news anchor Tom Brokaw to remain at the net through 2014.Under the deal, Brokaw will produce and anchor documentaries for the television web and for other Peacock properties. He also will serve as an NBC News analyst on major stories. Brokaw is skedded to step down as anchor of market leader NBC’s News’ “Nightly News” on Dec. 1, turning over his chair to Brian Williams. NBC chair-chief exec and GE vice chair Bob Wright pointedly acknowledged Brokaw during a news conference announcing the merger — and Brokaw’s new deal. “Much of the success of NBC News can be attributed directly to Brokaw,” Wright said.