The Boston Celtics on Monday defeated the Dallas Mavericks 106-88 in Game 5 of the NBA Finals to win a record 18th title. Boston’s Jayson Tatum led all scorers with 31 points, while also dishing 11 assists and grabbing eight rebounds. Fellow superstar Jaylen Brown added 21 points, eight boards and six assists as the duo led the Celtics to the decisive win at TD Garden in Boston. Brown was awarded the most valuable player (MVP), after also getting the nod in the Eastern Championship Finals. Al Horford finally became an NBA champion in his 186th playoff game, a record number of post-season games…