New document type for communication #1197
Description
This relates to #1164
A new type of document that allows to show an alert on a set of documents.
The specifications are given (in french) by @fbunoz here: https://forum.camptocamp.org/t/outil-de-communication-a-destination-des-institutionnels-et-autres-gestionnaires-de-site/252853/3
This may be subject to sponsorship.