First this is more consistent as we already have a website-build
directory. Then it is also useful for migrating to haunt as 'haunt
build' puts the generated website in a 'site/' directory, so without
this rename, when the migration would be complete we'd have site/site
instead of website/site.
Signed-off-by: Denis 'GNUtoo' Carikli <GNUtoo@cyberdimension.org>
