[system-administrators-guide] Remove link to old X Window System chapter

[stephenw]

commit e0709c9437e03b78ac35359cc4a0a1e2261e67f3
Author: Stephen Wadeley <swadeley at redhat.com>
Date:   Tue Dec 9 18:22:13 2014 +0100

    Remove link to old X Window System chapter

 en-US/Preface.xml |    8 --------
 1 files changed, 0 insertions(+), 8 deletions(-)
---
diff --git a/en-US/Preface.xml b/en-US/Preface.xml
index c8ddc16..618ad3d 100644
--- a/en-US/Preface.xml
+++ b/en-US/Preface.xml
@@ -159,14 +159,6 @@
           </para>
         </listitem>
       </varlistentry>
-      <varlistentry>
-        <term><xref linkend="ch-The_X_Window_System" /></term>
-        <listitem>
-          <para>
-            This appendix covers the configuration of the X Window System, the graphical environment used by &MAJOROS;. Read this appendix if you need to adjust the configuration of your X Window System.
-          </para>
-        </listitem>
-      </varlistentry>
     </variablelist>
   </section>
   <xi:include href="Common_Content/Conventions.xml" xmlns:xi="http://www.w3.org/2001/XInclude" />