doc: PG 16 relnotes, adjust subscription origin mention

Reported-by: Masahiko Sawada

Discussion: https://postgr.es/m/CAD21AoC+VihMWs3-xVB3Z=8LzLbsQc52TO29o25rzfqcnJDCUQ@mail.gmail.com

Author: bmomjian

doc/src/sgml/release-16.sgml

@@ -1459,7 +1459,7 @@ Allow logical replication subscribers to process only changes that have no origi
 </para>
 
 <para>
-This can be used to avoid replication loops.
+This can be used to avoid replication loops.  This is controlled by the new CREATE SUBSCRIPTION "origin" option.
 </para>
 </listitem>