Add more details to SQS queue

modules/postgres-etl/README.md

@@ -97,4 +97,4 @@ Contains environment variables for container `pg_restore` within **Load** ECS ta
 
 #### SQS Integration for ETL process
 
-The SQS queues are used to watch the S3 bucket in the Extract environment. We only need it in the `extract` module. The main queue `postgres-etl-s3` receives messages about the data extraction events and a dead-letter queue `postgres-etl-s3-dlq` handles messages that cannot be processed successfully.
+The SQS queues are used to watch the S3 bucket in the Extract environment. We only need it in the `extract` module. The main queue `postgres-etl-s3` receives messages about the data extraction events and a dead-letter queue `postgres-etl-s3-dlq` handles messages that cannot be processed successfully. Another component of the ETL process polls the `postgres-etl-s3` SQS queue for messages. When a message is received, it triggers the next steps in the ETL process such as processing the extracted data using Kubernetes jobs and Step Functions.