EnvVars Configuration README

[yerdua]

Current state:
The oracle is configured with EnvVars. All of these are documented in a giant table, sorted alphabetically. Some of these are essential. Some of them are flat-out ignored depending on the values of other EnvVars.

What could be better?
Being able to understand more easily which settings are important and what the relationships are among the settings. Empowering someone who runs an oracle to make informed choices about the settings, and everyone else to be more informed about how it works.

This would a readme file in the open oracle repo that could eventually help the public understand a bit more.