RDS/Aurora Docs clarifications.

[reillski]

Hi,

1. In the RDS docs, a limitation with binlog_format and pt-table-checksum is referenced. In Aurora MySQL version 3, users are able to set binlog_format at the session level natively. Could this information regarding aurora version 3 be added?

   
   mysql> select @@version,@@aurora_version,@@binlog_format;
   +-----------+------------------+-----------------+
   | @@version | @@aurora_version | @@binlog_format |
   +-----------+------------------+-----------------+
   | 8.0.32    | 3.05.2           | STATEMENT       |
   +-----------+------------------+-----------------+
   1 row in set (0.00 sec)

mysql> set session binlog_format='row'; Query OK, 0 rows affected (0.01 sec)

mysql> select @@version,@@aurora_version,@@binlog_format; +-----------+------------------+-----------------+ | @@version | @@aurora_version | @@binlog_format | +-----------+------------------+-----------------+ | 8.0.32 | 3.05.2 | ROW | +-----------+------------------+-----------------+ 1 row in set (0.00 sec)

2. 
> Aurora does not allow editing of the read_only parameter. While it is defined as {TrueIfReplica}, the parameter is non-modifiable field.

`read_only` can be modified in cluster parameter groups and from Aurora MySQL version 3.06 and higher via the `mysql.rds_set_read_only` stored procedure([details here](https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/mysql-stored-proc-replicating.html#mysql_rds_set_read_only) ).  Only caveat is reader instances are always set to `innodb_read_only=1` which cannot be modified. 

Thanks!
Marc