patch for books.html

Please update books.html with this new book addition. Thank you.

--- books.html.orig	2006-08-29 11:25:46.000000000 -0500
+++ books.html	2006-08-29 11:42:26.000000000 -0500
@@ -185,6 +185,20 @@
 <br>Apparently not available through Amazon.com, but <a href="http://www.lob.de/cgi-bin/work/frameset?flag=jfl&amp;frame=yes&amp;id=38effe1813566">
 Lehmann's Online Bookshop</a> lists it. However, you might want to pick up a <a href="http://www.lob.de/cgi-bin/work/frameset?flag=jfl&amp;frame=yes&amp;id=38effe1813566">more
 recent version of the CD-ROM</a>.
+</dd><dt>
+<i>The OpenBSD PF Packet Filter Book</i>
+</dt><dd>
+published by Reed Media Services
+</dd><dd>
+August 2006, 193 pp.
+</dd><dd>
+This book is an expanded, cross-referenced, index, edited, and reformatted version of the
+<a href="http://www.openbsd.org/faq/pf/index.html">PF User's Guide</a>.
+It also covers spamd and introduces the setup and differences of PF
+on NetBSD, DragonFly, and FreeBSD.
+<br />The official book website with table of contents, index, and
+configuration examples can be found at
+<a href="http://www.reedmedia.net/books/pf-book/">http://www.reedmedia.net/books/pf-book/</a>.
 </dd></dl>
 <hr>