Add reference to the NewbieDoc Docbook Guide.

doc/src/sgml/docguide.sgml

-<!-- $PostgreSQL: pgsql/doc/src/sgml/docguide.sgml,v 1.51 2004/11/15 06:32:13 neilc Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/docguide.sgml,v 1.52 2005/02/19 04:34:17 momjian Exp $ -->
 
 <appendix id="docguide">
  <title>Documentation</title>
@@ -65,7 +65,9 @@
    url="http://www.oasis-open.org/docbook">official DocBook
    site</ulink> has good introductory and reference documentation and
    a complete O'Reilly book for your online reading pleasure.  The
-   <ulink url="http://www.freebsd.org/docproj/docproj.html">FreeBSD
+   <ulink url="http://newbiedoc.sourceforge.net/metadoc/docbook-guide.html">
+   NewbieDoc Docbook Guide<</ulink> is very helpful for beginners.
+   The <ulink url="http://www.freebsd.org/docproj/docproj.html">FreeBSD
    Documentation Project</ulink> also uses DocBook and has some good
    information, including a number of style guidelines that might be
    worth considering.