Add source record for CNS (social security) death notification page

[TommiLindfors]

What needs doing

The Luxembourg Caisse Nationale de Santé (CNS) has a page about notifying them after a death. We need to create a source record for it.

Steps

1. Find the official CNS page about death notification / end of coverage
2. Create a new file: data/sources/lu/cns-death-notification.yaml
3. Follow the format in data/sources/lu/guichet-death-life-event.yaml as a template
4. Fill in: id, url, title, jurisdiction, languages, accessed_at, verification_status: discovered
5. Run python scripts/validate.py to check your file
6. Open a PR

Time estimate

~20 minutes

Skills needed

Basic YAML editing. No coding required.