Add PXE server configuration documentation

Signed-off-by: Nicolas Iooss <nicolas.iooss_git@polytechnique.org>
etc-desktop/X11: add example file to configure a French keyboard

Signed-off-by: Nicolas Iooss <nicolas.iooss_git@polytechnique.org>
etc/iptables: remove useless DHCP filters

Signed-off-by: Nicolas Iooss <nicolas.iooss_git@polytechnique.org>
Add etc-desktop/avahi/avahi-daemon.conf

Signed-off-by: Nicolas Iooss <nicolas.iooss_git@polytechnique.org>
Add etc-server/mysql/my.cnf MariaDB configuration file

Signed-off-by: Nicolas Iooss <nicolas.iooss_git@polytechnique.org>