doc: removal of bibliography book

In r52086 the reference from the FAQ was removed.  Remove a book
"bibliography" which is solely a reference to the outdated bibliography,
and not connected to the build.

en_US.ISO8859-1/books/bibliography/Makefile

@@ -1,25 +0,0 @@
-#
-# $FreeBSD$
-#
-#
-
-MAINTAINER=doc@FreeBSD.org
-
-DOC?= book
-
-FORMATS?= html
-
-INSTALL_COMPRESSED?= gz
-INSTALL_ONLY_COMPRESSED?=
-
-#
-# SRCS lists the individual XML files that make up the document. Changes
-# to any of these files will force a rebuild
-#
-
-# XML content
-SRCS=  book.xml
-
-DOC_PREFIX?= ${.CURDIR}/../../..
-
-.include "${DOC_PREFIX}/share/mk/doc.project.mk"

en_US.ISO8859-1/books/bibliography/book.xml

@@ -1,27 +0,0 @@
-<?xml version="1.0" encoding="iso-8859-1"?>
-<!DOCTYPE book PUBLIC "-//FreeBSD//DTD DocBook XML V5.0-Based Extension//EN" "http://www.FreeBSD.org/XML/share/xml/freebsd50.dtd" [
-<!ENTITY bibliography SYSTEM "../../../share/xml/bibliography.xml">
-]>
-<!--
-     The FreeBSD Documentation Project
-
-     $FreeBSD$
--->
-<book xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink" version="5.0" xml:lang="en">
-  <info>
-    <title>FreeBSD Bibliography</title>
-
-    <author><orgname>The FreeBSD Documentation Project</orgname></author>
-
-    <pubdate>$FreeBSD$</pubdate>
-
-    <copyright>
-      <year>2001</year>
-      <holder>The FreeBSD Documentation Project</holder>
-    </copyright>
-
-    <releaseinfo>$FreeBSD$</releaseinfo>
-  </info>
-
-  &bibliography;
-</book>