Fix typo in cdist-explorer

Thanks, henk!

15:53 < henk> telmich: s/Except/Expect/ in
http://www.nico.schottelius.org/software/cdist/man/latest/man7/cdist-explorer.html

Signed-off-by: Nico Schottelius <nico@freiheit.schottelius.org>