By Bill Trott (Reuters) -Former Boston Celtics star Bill Russell, one of the sports world’s greatest winners as the anchor of a team that won 11 NBA championships, as well as the league’s first black coach, died on Sunday at the age of 88. Russell, a five-time Most Valuable Player who was also outspoken on racial issues, passed away peacefully with his wife Jeannine by his side, according to a statement posted on his Twitter account that did not state a cause of death. “Bill Russell was the greatest champion in all of team sports,” NBA Commissioner Adam Silver said in a statement. “The countle…