added exp. what make update does

git-svn-id: http://svn.linuxfromscratch.org/LFS/trunk/BOOK@1179 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689

chapter06/nettools-exp.xml

@@ -0,0 +1,16 @@
+<sect2>
+<title>Command explanations</title>
+
+<para><userinput>make update:</userinput> This does the same as a
+<userinput>make install</userinput> with the exception that make update
+doesn't make backups of files it's replacing. One of the things
+net-tools replaces is sh-utils's version of
+<filename>/bin/hostname</filename> (net-tools's version is far better
+than sh-utils's version).</para>
+
+<para>Also, if you decide to reinstall this package at some point in the
+future, a <userinput>make update</userinput> won't backup all the files
+from a previous net-tools installation.</para>
+
+</sect2>
+