Minor: 4.3 Caching and cacheable OSCORE

[mkovatsc]

For IoT systems, object security [RFC8613] may be preferable over transport layer security, as it enables intermediaries to cache responses while preserving security.

"Cacheable OSCORE", Christian Amsuess, Marco Tiloca, 2021-10-25, <draft-amsuess-core-cachable-oscore-03.txt>
I guess this is why our wording is "may be" and "enables".. Should we add an explicit note?

[akeranen]

Added ref to the Cacheable OSCORE draft; let's see whether we can give more detailed guidance based on future learnings on the topic.