Since 1989 Oscar-nominated filmmaker Stanley Nelson has been among the leading chroniclers of Black liberation and civil rights struggles in the U.S. Some of the documentaries Nelson has directed and produced, such as 2003’s The Murder of Emmett Till, 2021’s Tulsa Burning: The 1921 Race Massacre and the 2021 short Lynching Postcards:‘Token of a Great Day’ — about souvenir postcards that…