add mongocredential setting

Author: stephmarie17

source/fundamentals/authentication/x509.txt

@@ -119,6 +119,7 @@ see the corresponding syntax:
              },
              UseTls = true,
              Server = new MongoServerAddress("<hostname>"[, "<port>"]),
+             Scheme = ConnectionStringScheme.MongoDBPlusSrv // Needed when connecting to MongoDB Atlas
          };
 
 Troubleshooting