Fix the example in the document of file-fdw

[btkatsuragiyu]

Although csvlog has the leader_pid field, the document of file-fdw
that uses csvlog as an example does not reflect this fact.
Concretely, the DDL for table definition does not have the leader_pid 
field.
This patch fixes the DDL in the document of file-fdw.
Regards,
Yuta Katsuragidiff --git a/doc/src/sgml/file-fdw.sgml b/doc/src/sgml/file-fdw.sgml
index eefc6e7e5b..8831f5911f 100644
--- a/doc/src/sgml/file-fdw.sgml
+++ b/doc/src/sgml/file-fdw.sgml
@@ -265,7 +265,8 @@ CREATE FOREIGN TABLE pglog (
   query_pos integer,
   location text,
   application_name text,
-  backend_type text
+  backend_type text,
+  leader_pid integer
 ) SERVER pglog
 OPTIONS ( filename 'log/pglog.csv', format 'csv' );
 </programlisting>