Add nofollow support to Hypermess

Hello,

While researching competitor incoming links, I was surprised to discover
that all of the mailing list archives
<https://lists.w3.org/Archives/Public/> don't qualify the links provided by
users as "not endorsed by the original author or publisher of the page" by
using your published HTML standard's nofollow keyword
<https://html.spec.whatwg.org/#link-type-nofollow>.

Now modifying the e-mail contents themselves is only needed for the public
website archives so would just be adding support for "Hypermess
<https://lists.w3.org/Archives/AboutArchives.html>" to append rel=nofollow
to a elements within the body of the e-mails. Please consider implementing
this when you can.

-- 
Thanks,
Josh Reynolds
IT & Marketing Manager
PLC Source <https://www.plcsource.com/> | everythingMRO
<https://www.everythingmro.com>