Docs: add a website's wiki

[EmileRolley]

As the current work is to extend the area of people contributing to the project (e.g. #637, #535, #71, etc...), it's important to have a minimal documentation.

This is done via the GitHub's wiki: nosgestesclimat-site's wiki.

Tasks

• Setup a CI to update the wiki with the content of the ./docs folder.
• Add pages:
  • Translation
    • Redirection page from the website's alert banner
    • Add information about units translation.
    • Complete non-tech user guide for translation
    • Custom publicodes mechanisms
  • PERSONNALISATION.md cloned into wiki/Customisation
  • Guide to update the documentation