Add an example on how to create a live CD with xorg.

Add an example on how to create a live CD with xorg.

To build one, you can use the following commands:

% cd /usr/src/nrelease
% make PKGSRC_PKG_PATH=/pkgsrc/dir/All release gui

See release(7) for more information.

Note that you will need pkgsrc binary packages locally. In the example above,
replace /pkgsrc/dir with the path where they are kept.

The resulting ISO will be /usr/release/dfly-gui.iso.