Doc: Fix typo in logicaldecoding.sgml.

Author: Hayato Kuroda <kuroda.hayato@fujitsu.com>
Backpatch-through: 17, where it was introduced
Discussion: https://postgr.es/m/OSCPR01MB149662EC5467B4135398E3731F532A@OSCPR01MB14966.jpnprd01.prod.outlook.com

doc/src/sgml/logicaldecoding.sgml

@@ -420,10 +420,10 @@ postgres=# select * from pg_logical_slot_get_changes('regression_slot', NULL, NU
     <para>
      When slot synchronization is configured as recommended,
      and the initial synchronization is performed either automatically or
-     manually via pg_sync_replication_slot, the standby can persist the
+     manually via <function>pg_sync_replication_slots</function>, the standby
-     synchronized slot only if the following condition is met: The logical
+     can persist the synchronized slot only if the following condition is met:
-     replication slot on the primary must retain WALs and system catalog
+     The logical replication slot on the primary must retain WALs and system
-     rows that are still available on the standby. This ensures data
+     catalog rows that are still available on the standby. This ensures data
      integrity and allows logical replication to continue smoothly after
      promotion.
      If the required WALs or catalog rows have already been purged from the