Keep content aligned with latest CFRG document

[rikard-sics]

Let's track how the content of the CFRG document develops. Up to v-09 there has been no new radical changes.

A related point is how much we should rely on the CFRG document. We could for instance reduce the scope of the limits section and only cover there the counting logic and OSCORE-relevant processing. Then for the rest we point to the document in CFRG .