Looks like "The Voice" gave Kelly Clarkson, Lionel Richie and Robin Thicke the TV mentoring bug.ABC has revealed that those three music superstars and Sugarland's frontwoman Jennifer Nettles will serve as mentors and singing partners on "Duets," the network's new signing reality competition that premieres this summer. Though the crowded genre already includes "American Idol," "The Voice," "The X Factor" and "America's Got Talent," "Duets" ...