title: AWS RDS: transaction level in Aurora replica
body: <p>We are using Amazon Aurora as a database for our web application.
  we set the transaction level to READ-COMMITTED for our primary instance by creating new  parameter group and attaching it to the primary instance to avoid locks.
  By default amazon replicas are using transaction level as REPEATABLE-READ by using default instance parameter group. 
  When replica is promoted as primary instance in case of failures, our primary instance's  transaction level is changing to(TRANSACTION ISOLATION=REPEATABLE-READ ).
  we wanted to set the transaction level to READ-COMMITTED instead of REPEATABLE-READ when replica(reader) is promoted as primary instance(writer). it would be great if anyone provide a way to achieve this.</p>