document the new preferences.d folder in apt_preferences(Closes: #544017)

debian/changelog

@@ -29,6 +29,8 @@ apt (0.7.24) UNRELEASED; urgency=low
       a bit and improve the documentation for this option group.
   * doc/apt.ent, all man pages:
     - move the description of files to globally usable entities
+  * doc/apt_preferences.5.xml:
+    - document the new preferences.d folder (Closes: #544017)
 
  -- David Kalnischkies <kalnischkies@gmail.com>  Fri, 28 Aug 2009 09:40:08 +0200
 

doc/apt_preferences.5.xml

@@ -32,7 +32,8 @@
 <refsect1>
 <title>Description</title>
 <para>The APT preferences file <filename>/etc/apt/preferences</filename>
-can be used to control which versions of packages will be selected
+and the fragment files in the <filename>/etc/apt/preferences.d/</filename>
+folder can be used to control which versions of packages will be selected
 for installation.</para>
 
 <para>Several versions of a package may be available for installation when
@@ -610,6 +611,13 @@ apt-get install <replaceable>package</replaceable>/sid
 </refsect2>
 </refsect1>
 
+<refsect1>
+<title>Files</title>
+  <variablelist>
+    &file-preferences;
+  </variablelist>
+</refsect1>
+
 <refsect1>
 <title>See Also</title>
 <para>&apt-get; &apt-cache; &apt-conf; &sources-list;