By now, the game plan is all-too familiar: Build an enormous library of content, then charge people a small monthly fee for access to it. Spotify did it with music. Netflix did it with video. Now Scribd, a 10-year-old startup that counts more than a half-million subscribers, wants to apply that same formula to news. Scribd has now scored licensing agreements with leading publishers to target their existing 500,000 paid customer base.