Staking returns figure

[paulhauner]

There is a "reward calculator" when creating a validator which shows ETH returns as a weekly/monthly/annual rate.

I think we need to do two things with this:

1. Confirm that we want to include this
2. If we want to include it, lock in a percentage (I expect this to be circa-15%).

[daniel-flex]

The annual rewards multiplier can be set in the .env file, but not easily adjustable without redeployment