Port the MapMap Web site to a multi-page

[aalex]

Port the MapMap Web site to a multi-page

Criteria

• Keep the current how-to document
• Multilingual (fr, es, de, en to start with)
• Add some about page

Tech details

• We could use Astro.
• See https://docs.github.com/en/pages/getting-started-with-github-pages/creating-a-github-pages-site