Add a Papyru smodeling guide by All4tech (from https://github.com/openETCS/model-evaluation/tree/master/model/Papyrus-CEA-All4tec/papyrus_guidelines)

Signed-off-by: MatthieuPERIN <matthieu.perin@cea.fr>
Merge branch 'master' of https://github.com/openETCS/toolchain.git