Add Learn Linux The Hard Way guide

free-programming-books.md

@@ -961,6 +961,7 @@ See also [TeX](#tex)
 * [Getting Started with Ubuntu](http://ubuntu-manual.org/)
 * [GNU Autoconf, Automake and Libtool](http://sources.redhat.com/autobook/download.html)
 * [GTK+/Gnome Application Development](http://www.linuxtopia.org/online_books/gui_toolkit_guides/gtk+_gnome_application_development/index.html)
+* [Learn Linux The Hard Way](http://nixsrv.com/llthw)
 * [Linux Advanced Routing & Traffic Control HOWTO](http://lartc.org/)
 * [The Debian Administrator's Handbook](http://debian-handbook.info/)
 * [The Linux Command Line](http://linuxcommand.org/tlcl.php) (PDF)