Added nodump roles to the 'aboutlfs' section

git-svn-id: http://svn.linuxfromscratch.org/LFS/trunk/BOOK@6839 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689

chapter04/aboutlfs.xml

@@ -12,14 +12,14 @@ be used several times. It is paramount that this variable is always defined.
 It should be set to the mount point chosen for the LFS partition.
 Check that the <envar>LFS</envar> variable is set up properly with:</para>
 
-<screen><userinput>echo $LFS</userinput></screen>
+<screen role="nodump"><userinput>echo $LFS</userinput></screen>
 
 <para>Make sure the output shows the path to the LFS partition's mount
 point, which is <filename class="directory">/mnt/lfs</filename> if the
 provided example was followed. If the output is incorrect, the
 variable can be set with:</para>
 
-<screen><userinput>export LFS=/mnt/lfs</userinput></screen>
+<screen role="nodump"><userinput>export LFS=/mnt/lfs</userinput></screen>
 
 <para>Having this variable set is beneficial in that commands such as
 <command>mkdir $LFS/tools</command> can be typed literally. The shell