Add Jenkinsfile for website depolyment

As an Apertis developer doing a release, I want the web page on
images.apertis.org to be automatically updated from the updates done to
apertis-image-recipes.git.

The website is stored at images.apertis.org:/srv/images.apertis.org/www.
It used to be stored in the apertis-image-customization repo, but it has
been updated by hand directly on the server recently.

Here is a Jenkinsfile to depoly the website automaticlly.

Signed-off-by: Andrew Lee (李健秋) <andrew.lee@collabora.com>
Reviewed-by: Héctor Orón Martínez <hector.oron@collabora.co.uk>
Reviewed-by: Emanuele Aina <emanuele.aina@collabora.com>
Reviewed-by: Andrew Shadura <andrew.shadura@collabora.co.uk>
Differential Revision: https://phabricator.apertis.org/D7651