Update README.md

Author: cbaker6

README.md

@@ -527,7 +527,25 @@ let api = new ParseServer({
 
 ### Notes <!-- omit in toc -->
 
-- This feature is currently only available for MongoDB and not for Postgres.
+- There are no additional steps needed to use this feature with MongoDB
+- For Postgres, you will need to create a cron job, use [pgAdmin](https://www.pgadmin.org/docs/pgadmin4/development/pgagent_jobs.html), or similar to call the Postgres function, `idempodency_delete_old_rows()`. For example, the cron job can call the script below (make sure the script has the same priveledges to log into Postgres as your Parse Server):
+
+```bash
+#!/bin/bash
+
+set -e
+psql -v ON_ERROR_STOP=1 --username "$POSTGRES_USER" --dbname "$POSTGRES_DB" <<-EOSQL
+    SELECT idempodency_delete_old_rows();
+EOSQL
+
+exec "$@"
+```
+
+Assuming the script above is named, `parse_idempodency_delete_old_rows.sh`, a cron job that runs the script every 2 minutes may look like:
+
+```bash
+2 * * * * /root/parse_idempodency_delete_old_rows.sh >/dev/null 2>&1
+```
 
 ## Localization