added note that warning about 'su' is safe to ignore

git-svn-id: http://svn.linuxfromscratch.org/LFS/trunk/BOOK@1640 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689

chapter05/shellutils-inst.xml

@@ -21,5 +21,17 @@ cd $LFS/usr/bin &&
 mv basename date echo false hostname $LFS/bin &&
 mv pwd sleep stty test true uname $LFS/bin &&
 mv chroot ../sbin</userinput></screen></para>
+
+<para>During the make install stage you will see the following warning:</para>
+
+<blockquote><screen>WARNING: insufficient access; not installing su
+NOTE: to install su, run 'make install-root' as root</screen></blockquote>
+
+<para>You can safely ignore that warning. You need to be logged in as root
+in order to install su the way sh-utils wants to install it, that being
+suid root. Because we don't need su during chapter 6, and su will be properly
+installed when we re-install sh-utils in chapter 6 anyways, you can just
+pretend you didn't see it.</para>
+
 </sect2>