Improve documentation on WAL disk space usage for Postgres connector

The existing documentation for Postgres Connector regarding WAL Disk Space usage can be improved. While we are working with AWS RDS, we have also WAL Disk Space usage increase on an idle database for test environment. After searching around, I came across this article here: https://wolfman.dev/posts/pg-logical-heartbeats/ explaining why new WAL files are recorded eventhough there is a new update to the monitored database tables.

My suggestion: To point out that AWS RDS have a different behaviour in contrast to a normal Postgres Database and the reason for new entries for WAL Logs being written, so that people do not lose time while working on an idle AWS RDS environment.