How to document the archetypes

[nsryan2]

There needs to be some commitment to how this will be documented. I think it will be a little hodgepodge, but the plan is to use very descriptive README's and example notebooks.

This issue can be closed with a clear, well-documented decision on how information will be stored in this repo.

[nsryan2]

As these archetypes piggy-back off of the Cycamore Reactor, we will reference the existing documentation (https://fuelcycle.org/user/cycamoreagents.html#cycamore-reactor) as the majority of the features are the same. The new features will be documented through the READMEs and with example notebooks.