Rédiger la documentation

• https://stackoverflow.com/questions/60530676/can-gitlab-pages-be-used-for-review-apps-on-a-mkdocs-project
• https://gitlab.com/gitlab-org/gitlab/-/issues/16907#note_214936412
• https://gitlab.com/gitlab-org/gitlab/-/issues/16907#note_555813854
• https://gitlab.com/gitlab-com/www-gitlab-com/-/blob/6ffcdc3cb9af2abed490cbe5b7417df3e83cd76c/.gitlab-ci.yml#L332