Fix indexterms

doc/src/sgml/plsql.sgml

 <!--
-$Header: /cvsroot/pgsql/doc/src/sgml/Attic/plsql.sgml,v 2.45 2001/10/13 04:58:35 momjian Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/Attic/plsql.sgml,v 2.46 2001/11/08 23:41:12 petere Exp $
 -->
 
 <chapter id="plpgsql"> 
@@ -1727,11 +1727,11 @@ CREATE FUNCTION c_overpaid (EMP, INTEGER) RETURNS BOOLEAN AS '
 
   <title>Porting from Oracle PL/SQL</title>
 
-  <indexterm>
+  <indexterm zone="plpgsql-porting">
    <primary>Oracle</primary>
   </indexterm>
 
-  <indexterm>
+  <indexterm zone="plpgsql-porting">
    <primary>PL/SQL</primary>
   </indexterm>