reboot: use umount -R to simplify the commands

git-svn-id: http://svn.linuxfromscratch.org/LFS/trunk/BOOK@12146 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689

chapter11/reboot.xml

@@ -75,24 +75,9 @@
 
 <screen><userinput>logout</userinput></screen>
 
-  <para>Then unmount the virtual file systems:</para>
+  <para>Unmount the LFS file system hierarchy:</para>
 
-<screen><userinput>umount -v $LFS/dev/pts
-umount -v $LFS/dev
-umount -v $LFS/run
-umount -v $LFS/proc
-umount -v $LFS/sys</userinput></screen>
-
-  <para>If multiple partitions were created, unmount the other
-  partitions before unmounting the main one, like this:</para>
-
-<screen role="nodump"><userinput>umount -v $LFS/usr
-umount -v $LFS/home
-umount -v $LFS</userinput></screen>
-
-  <para>Unmount the LFS file system itself:</para>
-
-<screen><userinput>umount -v $LFS</userinput></screen>
+<screen><userinput>umount -Rv $LFS</userinput></screen>
 
   <para>Now, reboot the system with:</para>