Add documentation / process what and how to test new rollups

[andfletcher]

Issue Description

Acceptance Criteria

[andfletcher]

We should check/make sure that we have an apparent document on what tests/challenges/invalidations etc, we need to do and how we need to do them when we add a new rollup.

We have this document, but we should make sure everyone in the team understands it: https://docs.google.com/spreadsheets/d/1w8CgERbHG5WDgW1ib9IU6_jLzPxmhudMnkriWbAKXUE/edit?pli=1#gid=0

[andfletcher]

https://docs.google.com/spreadsheets/d/1GQIJcDtIgIWEfFmpuNdlUWz7z1EGOPNf/edit#gid=1237218617

[andfletcher]

1646 block by this issue

[fredo]

Created https://docs.google.com/document/d/1_G6u7N7RKvd2Jl2W3TbF1sXkDTqrqjUFZNQ99EvNHZQ/edit?usp=sharing

and documents in

https://drive.google.com/drive/folders/1kFOHEH9T9RUEvoMWPnlbbev18XrK--zS