Delete description of trigger file

[Shinya Kato]

Hi,

Standby database promotion by trigger file creation is no longer 
supported from v16, but its description is remained.
So, I created a patch. Do you think?
--
Regards,
Shinya Kato
NTT DATA GROUP CORPORATIONdiff --git a/doc/src/sgml/high-availability.sgml b/doc/src/sgml/high-availability.sgml
index eb81260bbf..bd6e61ba8a 100644
--- a/doc/src/sgml/high-availability.sgml
+++ b/doc/src/sgml/high-availability.sgml
@@ -648,7 +648,7 @@ protocol to make nodes agree on a serializable transactional order.
     later disconnected, the standby goes back to step 1 and tries to
     restore the file from the archive again. This loop of retries from the
     archive, <filename>pg_wal</filename>, and via streaming replication goes on until the server
-    is stopped or failover is triggered by a trigger file.
+    is stopped.
    </para>
 
    <para>