Add a "SignedInfo Conventions" section

[johngray-dev]

From: EntrustCorporation/draft-ounsworth-composite-sigs#136

Make-like-picture from
https://datatracker.ietf.org/doc/html/draft-ietf-lamps-cms-sphincs-plus-03#name-signed-data-conventions

We also need to add SMIME-CAPS to the ASN.1. See the draft-cms-sphincs-plus

Doing this saves writing a separate draft of using this draft in CMS... Use link from Mike above SPHINCS template.

[johngray-dev]

Action: John to take a look at this (from what Mike did in Composite KEM), with the idea that maybe lamps will want us to put it in a separate document. To present this section next meeting (June 19th).

[johngray-dev]

Issue resolved in Pull request #13