./Walls could not be cloned. Make sure it’s using https:// and that it’s a public repo. See https://docs.github.com/en/github/working-with-github-pages/troubleshooting-jekyll-build-errors-for-github-pages-sites#invalid-submodule".foam to run with [[restructured-text]] (not just Markdown),
see foambubble/foam#474.