Please update free S/MIME certificate providers list

[dpward]

Please revise the Getting an S/MIME certificate page:

• The link for InstantSSL should be changed to: https://www.instantssl.com/secure-email ... tes-s-mime
• InstantSSL is a product of Comodo (which recently changed its name to Sectigo). Comodo/Sectigo does not have a separate free S/MIME offering — the link for it here is redundant and should be removed.
• Secorio is an "Affiliated Partner of Sectigo (formerly Comodo CA)". Likewise, it does not have a separate free S/MIME offering, but directs users to InstantSSL. The link for it here is also redundant and should be removed.
• On the InstantSSL page above, the free certificate is now referred to as a "Trial E-mail Certificate", and the link to obtain it says "Try Now". This goes to the same automated form that existed in the past, but they have also reduced the duration of the automatically issued certificates from 1 year to 30 days.

See also this recent comment which seems to have been lost in a different discussion.

[tanstaafl]

Thanks. I'll update it once the KB is back on-line.

edited: Done.