added note to be root before chrooting

git-svn-id: http://svn.linuxfromscratch.org/LFS/trunk/BOOK@1924 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689

chapter06/chroot.xml

@@ -3,7 +3,10 @@
 <?dbhtml filename="chroot.html" dir="chapter06"?>
 
 <para>It's time to enter our chroot'ed environment in order to install the
-rest of the software we need.</para>
+rest of the software we need. Before you can chroot you need to change to
+the <emphasis>root</emphasis> user since only user
+<emphasis>root</emphasis> can use the <userinput>chroot</userinput>
+command.</para>
 
 <para>Enter the following commands to enter the chroot'ed environment. From
 this point on there's no need to use the $LFS variable anymore, because