[system-administrators-guide] Bump link to Instal.Guide. 21

[stephenw]

commit edf47c06bff6d538561efa1ac040e8fd36b098a5
Author: Stephen Wadeley <swadeley at redhat.com>
Date:   Tue Dec 9 19:14:42 2014 +0100

    Bump link to Instal.Guide. 21

 en-US/Preface.xml |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/en-US/Preface.xml b/en-US/Preface.xml
index d25421e..04e67d8 100644
--- a/en-US/Preface.xml
+++ b/en-US/Preface.xml
@@ -30,7 +30,7 @@
   <section id="sect-Preface-Target_Audience">
     <title>Target Audience</title>
     <para>
-      The <citetitle pubwork="book">System Administrator's Guide</citetitle> assumes you have a basic understanding of the &MAJOROS; operating system. If you need help with the installation of this system, refer to the <ulink url="http://docs.fedoraproject.org/en-US/Fedora/19/html/Installation_Guide/index.html">&MAJOROSVER; Installation Guide</ulink>.
+      The <citetitle pubwork="book">System Administrator's Guide</citetitle> assumes you have a basic understanding of the &MAJOROS; operating system. If you need help with the installation of this system, refer to the <ulink url="http://docs.fedoraproject.org/en-US/Fedora/21/html/Installation_Guide/index.html">&MAJOROSVER; Installation Guide</ulink>.
       <!-- &ENTITIES; are stripped from URLs by transifex, so hardcoding is better for now -->
     </para>
   </section>