Updated Documentation

[Baelfur]

Hey i'm having a real hard time trying to understand what the current main branch supports in conjunction with the published documentation

https://api-umbrella.readthedocs.io/en/latest/getting-started.html#setup

this commit leads me to believe that Umbrella is now compatible with elastic v5 or 6, is that the case?

https://github.com/NREL/api-umbrella/pull/413

if so is there some alternative in progress documentation that I could reference?