add contributor in each page

On each page, we need to add contributing author on each page, for instance :

Could be in the front matter, so it is rendered automatically, and if needed later, we could create a table from this.

added Technical label

changed milestone to %Preprint

assigned to @ftesson

added DefenseSystem label

removed DefenseSystem label

changed milestone to %fixed before hackaton

mentioned in merge request !20 (merged)

mentioned in commit f12e1f15

closed with merge request !20 (merged)