Activision has announced that Call of Duty: Modern Warfare 4 will have day-one DLC, and like in years past, it will focus on a real-life military hero, with proceeds going to charity. The Call of Duty Endowment Valor Pack, launching on October 23 alongside the game, adds the real-life Medal of Honor recipient Kyle Carpenter to the game as a playable character. Carpenter was in Marjah, Afghanistan, when, on November 21, 2010, he put himself in front of a grenade…