关于MongoDB聚合框架，我能得到你的帮助吗？我试图从以下游戏集合中构建一个英超联赛表:{"_id":ObjectId("5b39fec4b5f8df161d259f36"),"gameWeek":1,"homeTeam":"Arsenal","awayTeam":"Leicester","homeGoals":2,"awayGoals":1},{"_id":ObjectId("5b39ffc2b5f8df161d259f6d"),"gameWeek":2,"homeTeam":"Arsenal","awayTeam":"Sunderland","homeGoals":1,"away