As noted by stronglikedan, the process to comment on an RFC is to send email to the author of the RFC, or alternatively, to the email list for the IETF Working Group from which the RFC came.

In this case, that would be the general Apps Area Working Group ( https://datatracker.ietf.org/wg/appsawg/charter/ ) and so comments could be sent to that list. Although sending to the author is probably the best initial route.

If the author receives enough comments to justify a new version, the process would then begin to publish a new version that would then obsolete the older version.

I would note that this particular document (the original RFC 7763 that is the origin for this HN thread) started discussion back in July 2014 with https://tools.ietf.org/html/draft-seantek-text-markdown-medi... and evolved over time until this publication now.

There's no way to comment on the website directly, so I think they are requesting that comments be submitted via email. I found this towards the bottom:

> Contact Information:

> (individual) John Gruber <http://daringfireball.net/>

> <comments@daringfireball.net>