Fix GH-2198: Typo in pg_insert() example

Author: cmb69

reference/pgsql/functions/pg-insert.xml

@@ -127,7 +127,7 @@
   // This is safe somewhat, since all values are escaped.
   // However PostgreSQL supports JSON/Array. These are not
   // safe by neither escape nor prepared query.
-  $res = pg_insert($dbconn, 'post_log', $_POST, PG_DML_ESCAPE);
+  $res = pg_insert($dbconn, 'post_log', $_POST, PGSQL_DML_ESCAPE);
   if ($res) {
       echo "POST data is successfully logged\n";
   } else {