Add WITH as a refname to the SELECT reference page.

Now "\help WITH" works and there will be a separate WITH(7) man page.

doc/src/sgml/ref/select.sgml

 <!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/select.sgml,v 1.108 2008/11/14 10:22:47 petere Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/select.sgml,v 1.109 2008/11/19 12:21:57 petere Exp $
 PostgreSQL documentation
 -->
 
@@ -12,6 +12,7 @@ PostgreSQL documentation
 
  <refnamediv>
   <refname>SELECT</refname>
+  <refname>WITH</refname>
   <refpurpose>retrieve rows from a table or view</refpurpose>
  </refnamediv>
 
@@ -19,6 +20,11 @@ PostgreSQL documentation
   <primary>SELECT</primary>
  </indexterm>
 
+ <indexterm zone="sql-select">
+  <primary>WITH</primary>
+  <secondary>in SELECT</secondary>
+ </indexterm>
+
  <refsynopsisdiv>
 <synopsis>
 [ WITH [ RECURSIVE ] <replaceable class="parameter">with_query</replaceable> [, ...] ]