LICENSE.md is not Markdown
This is also new to me, but: There are no official Markdown versions of CC licenses. You are using the official plain-text version, but with a markdown file extension. The result looks somewhat arbitrary, when looked at as HTML, e.g. on GitLab. Should the markdown file-extension be removed? Alternatively, we could use an inofficial Markdown version of the license, which would still be legal, as only formatting changes, but would probably not be detected as the correct license, for example by GitLab.