Fix misspelling. Thanks to 'unidentified-dud' on IRC for the report

git-svn-id: http://svn.linuxfromscratch.org/LFS/branches/systemd@10783 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689

chapter07/systemd-custom.xml

@@ -29,7 +29,7 @@
   <sect2>
     <title>Disabling Screen Clearing at Boot Time</title>
 
-    <para>The normal behavior for systemd is to clear the secreen at
+    <para>The normal behavior for systemd is to clear the screen at
     the end of the boot sequence. If desired, this behavior may be
     changed by running the following command:</para>