Add documentation for array_upper/lower().

doc/src/sgml/array.sgml

-<!-- $Header: /cvsroot/pgsql/doc/src/sgml/array.sgml,v 1.22 2002/09/21 18:32:52 petere Exp $ -->
+<!-- $Header: /cvsroot/pgsql/doc/src/sgml/array.sgml,v 1.23 2002/11/10 00:32:16 momjian Exp $ -->
 
 <sect1 id="arrays">
  <title>Arrays</title>
@@ -195,7 +195,9 @@ SELECT array_dims(schedule) FROM sal_emp WHERE name = 'Carol';
 
   <function>array_dims</function> produces a <type>text</type> result,
   which is convenient for people to read but perhaps not so convenient
-  for programs.
+  for programs.  <function>array_upper</function> and <function>
+  array_lower</function> return the upper/lower bound of the
+  given array dimension, respectively.
  </para>
 
  <para>