added a note that the sed's may cause the entire compile job to fail

git-svn-id: http://svn.linuxfromscratch.org/LFS/trunk/BOOK@1155 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689

chapter05/fileutils-inst.xml

@@ -28,5 +28,9 @@ not, then you need to re-do the installation using the sed commands if
 you didn't use them, or without the sed commands if you did use 
 them.</para>
 
+<para>Note that in some cases using these sed commands will result in
+problems not being able to compile this at package at all. If that's the
+case, start over again and don't use the sed commands.</para>
+
 </sect2>