This one has 4 choices, it shows how a category can trigger a specific
header, footer or watermark. Also validate the XML file against the XSD
as part of the build.

Change-Id: Id6cf3de63e7fadd16366465c7721d6052c7c60ed
Reviewed-on: https://gerrit.libreoffice.org/22615Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Jenkins <ci@libreoffice.org>