Write a post describing how each use case tree would work with Chrome

[pkotwicz]

I am placing this bug as a placeholder to remind myself. This might need to wait till Sam Goto gets back from vacation.

[pkotwicz]

I have asked Sam Goto to flesh out the use case trees because he knows best the future direction of the FedCM API

[pkotwicz]

I have posted a PR with draft decision trees for Chrome