Upgrade: Wording fix ('upgrade' instead of 'update')

Author: cwickert

xml/sle_update_preparation.xml

@@ -753,8 +753,8 @@ postgres &gt; <command>exit</command></screen>
   <para>
    If your machine serves as a &vmhost; for &kvm;<phrase os="sles;sled"> or
    &xen;</phrase>, make sure to properly shut down all running &vmguest;s prior
-   to the update. Otherwise you may not be able to access the guests after the
-   update.
+   to the upgrade. Otherwise you may not be able to access the guests after the
+   upgrade.
   </para>
  </sect1>
  <sect1 os="sles;sled" xml:id="sec-update-preparation-rmt">