CMS didn't make the 6.6 release: adjust the text in the HISTORY sections

Tweak cross references, in particular making sure that
all CMS pages are linked to CMS_ContentInfo_new(3) both ways
and that closely related pages reference each other.

minor cleanup:
* mark up ASN.1 type and field names
* move the RFC reference to STANDARDS
* and minor wording improvements

bring HISTORY sections up to OpenBSD standards

Re-convert and re-import the CMS manual pages from OpenSSL 1.1.1
(which are still under a free license) with pod2mdoc(1) now that
jsing@ has begun work to provide these APIs.
Some formatting was impr

Re-convert and re-import the CMS manual pages from OpenSSL 1.1.1
(which are still under a free license) with pod2mdoc(1) now that
jsing@ has begun work to provide these APIs.
Some formatting was improved and some typos were fixed, but apart
from that, little was changed, so there is still much to polish.

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Convert and enable CMS manuals.
Already some time ago, bcook@ said these can be installed.