William Sherman, a McKinney High School junior with down syndrome, captured hearts on social media last month when a video of him hitting shots and celebrating during a varsity versus faculty basketball game spread online. That joy reached the Dallas Mavericks. The team invited William and his family to Sunday night’s game against the Toronto Raptors, treating them to a VIP experience that included a special dinner, pregame warmups with the players, and courtside memories that William won’t soon