Document considerations for report lifetime.

[hdevalence]

Branching out of discussions on the Zoom call comparing the CEN protocol with the STRICT protocol documented here: https://github.com/ito-org/STRICT

The STRICT protocol is similar to the strawman protocol described in the CEN protocol. One suggestion is that by using the CEN protocol with very short report lifetimes, it may be possible to provide the functionality of the STRICT protocol using the CEN protocol.

However, to determine whether this is even possible, it's important to analyze the effect of report lifetimes.