SUNDAY Ken Jennings of “Jeopardy!” fame is one of the “Game Show Super Contestants” profiled in this new edition of the docu-series “Cover Story.” 7 p.m. GSN In his house at R’lyeh, dead Cthulhu awaits his cameo in an all-new “Treehouse of Horror” on “The Simpsons.” 8 p.m. Fox The bewitching Cassie...