add sh-utils patch comment

git-svn-id: http://svn.linuxfromscratch.org/LFS/trunk/BOOK@1052 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689

chapter05/shellutils-inst.xml

@@ -12,5 +12,8 @@ to be unpacked.</para>
 <userinput>mv -f date echo false pwd stty $LFS/bin &amp;&amp;</userinput>
 <userinput>mv -f su true uname hostname $LFS/bin</userinput></screen></para>
 
+<para>The patch file only needs to be applied if you are running
+glibc-2.1.x on your base system.</para>
+
 </sect2>