Kristen Bell's husband, Dax Shepard, who just celebrated 16 years of sobriety, and nobody was prouder than the couple’s two daughters who wrote him a heartfelt message on his special day.Kristen, 40, shared the handwritten sign from their children, Lincoln, seven, and Delta, five, to Instagram on Wednesday, and her fans and famous friends were quick to applaud the message.The note simply said: "Happy sobriety birthday Dady [sic]" but Kristen gave a lengthy explanation in the caption.MORE: How