Update pg_backup.sh

pg_backup.sh

@@ -4,9 +4,7 @@
 
 set -e
 
-# discourse/postgres keeps the live cluster at a versioned PGDATA under the
-# /var/lib/postgresql mount. Write the dump at the volume root so backupbot's
-# `postgresql_data.path: backup.sql` label captures it.
+# constants 
 BACKUP_FILE='/var/lib/postgresql/backup.sql'
 DATADIR="${PGDATA:-/var/lib/postgresql/18/docker}"
 DB_NAME="${POSTGRES_DB:-discourse}"