Need description on the overall get, update, and merge process for profiles.

[JGSweets]

All calculations should have a get, update, and merge.

Where get -> calcs from raw data.
merge -> takes two existing calcs and merges them
update -> takes in new data to add; get + merge

We need to add this description to the docs so one can add new calculations.

Also, eventually need to update all existing calcs to follow this paradigm.