Doc: Fix syntax error with db_parameter and db_options

[glensc]

what

❯ tf plan
╷
│ Error: Missing attribute separator
│ 
│   on main.tf line 41, in module "rds_instance":
│   41:     { name  = "myisam_sort_buffer_size"   value = "1048576" },
│ 
│ Expected a newline or comma to mark the beginning of the next attribute.
╵
❯ tf plan
╷
│ Error: Missing attribute separator
│ 
│   on main.tf line 48, in module "rds_instance":
│   48:         { name = "SERVER_AUDIT_EVENTS"           value = "CONNECT" },
│ 
│ Expected a newline or comma to mark the beginning of the next attribute.
╵

why

references