The screenwriting version of Markdown called Fountain
includes two features that I’ve always liked.
One called Notes and the other called Boneyard.
If you want to insert a Note (what programmers would call a comment) that will be totally ignored during conversion, one uses
[[ note or comment here ]]
If you want a section to be totally ignored, then we use boneyard, in which case, anything between /* and */ will be ignored, even if its whole pages of info.
I’m aware that it’s possible to use <-- --!> to accomplish something like it when using pandoc, but that text is still visible when viewing source, I believe.
Writers collaborating or making notes to themselves don’t want their notes in the final presentation product.
Just a thought.