🚚 Prevent the endless update train when fix script reports errors

[rix0rrr]

The problem was that the script would write to a .txt file, which would subsequently get committed and trigger another update which would post again, etc.

Fixed by writing to .md.tmp files, and gitignoring .tmp files. While we're at it, make the comment a bit nicer to read as well by outputting MarkDown instead of plain text.