Photo: Duffy Daugherty's Time magazine cover, Oct. 8, 1956. To Coach Mel Tucker: Welcome back to Michigan State. Welcome back to college football, 2020. You've got plenty on your mind now that the Big Ten has re-launched its season, so here s a refresher course on what Duffy Daugherty's Underground Railroad players and the southern Black high school coaches that laid the tracks meant to changing the face of college football. Your two seasons as a graduate assistant…