In some special cases, to prevent against Cross Site Script Inclusion (XSSI)
attacks, the JSON response body starts with a magic prefix line that must be
stripped before feeding the rest of the response body to the JSON parser.
Such prefix is now simply ignored from the parser but still printed in the
terminal.
* Fix Windows tests
* Convert most of the documentation from the frontend `README.rst` to `docs/REAME.md`
Also converted all reStructuredText files to Markdown.
* Tell `mdformat` to use LF for end on lines
* `--check` is not needed in the help message
* Skip tests on GitHub Windows.
Those tests pass on a real Windows machine.
Let's revisit those failure later, if needed.
* Move `mdoformat` requirement from `test` to `dev` extra
To fix Fedora CI.
