Documentation
Short and specific. Six pages covering the concepts you need to predict what the system will do.
How the pieces fit
Apps, requests, environments and versions — the four words that explain everything else.
The final checks
What has to pass before your app goes live, and what happens when it doesn't.
Saved versions and going back
What is saved, what can be brought back today, and why going back moves forward.
Where your app lives
One home, one database, and how its keys are kept.
Credit and what things cost
How usage is counted, what the number means, and what is never counted.
Taking your code and leaving
There is no export step, because there is nothing proprietary to export from.