bson.M{{
     "role": "myClusterwideAdmin"
     "privileges": []bson.M{
       { "resource": { "cluster": true }, "actions": []string{ "addShard" }},
     ],
     roles: []bson.M{{ "role": "read", "db": "admin" }},
},{ 
   "w": "majority" , "wtimeout": 5000}.
}}