Add some missing "See Also" entries to the domain-related SQL reference

pages. From Robert Treat.

doc/src/sgml/ref/alter_domain.sgml

 <!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/alter_domain.sgml,v 1.13 2004/11/27 21:27:07 petere Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/alter_domain.sgml,v 1.14 2005/05/02 01:52:50 neilc Exp $
 PostgreSQL documentation
 -->
 
@@ -208,6 +208,16 @@ ALTER DOMAIN zipcode DROP CONSTRAINT zipchk;
    <productname>PostgreSQL</productname> extension.
   </para>
  </refsect1>
+
+ <refsect1 id="SQL-ALTERDOMAIN-see-also">
+  <title>See Also</title>
+
+  <simplelist type="inline">
+   <member><xref linkend="sql-createdomain" endterm="sql-createdomain-title"></member>
+   <member><xref linkend="sql-dropdomain" endterm="sql-dropdomain-title"></member>
+  </simplelist>
+ </refsect1>
+
 </refentry>
 
 <!-- Keep this comment at the end of the file

doc/src/sgml/ref/create_domain.sgml

 <!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/create_domain.sgml,v 1.21 2005/05/01 15:57:59 tgl Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/create_domain.sgml,v 1.22 2005/05/02 01:52:50 neilc Exp $
 PostgreSQL documentation
 -->
 
@@ -203,7 +203,6 @@ CREATE TABLE us_snail_addy (
 
 </refentry>
 
-
 <!-- Keep this comment at the end of the file
 Local variables:
 mode: sgml

doc/src/sgml/ref/drop_domain.sgml

 <!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/drop_domain.sgml,v 1.14 2003/11/29 19:51:38 pgsql Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/drop_domain.sgml,v 1.15 2005/05/02 01:52:50 neilc Exp $
 PostgreSQL documentation
 -->
 
@@ -93,8 +93,10 @@ DROP DOMAIN box;
 
   <simplelist type="inline">
    <member><xref linkend="sql-createdomain" endterm="sql-createdomain-title"></member>
+   <member><xref linkend="sql-alterdomain" endterm="sql-alterdomain-title"></member>
   </simplelist>
  </refsect1>
+
 </refentry>
 
 <!-- Keep this comment at the end of the file