Share the Design Docs for the autoscaling implementation

[akanso]

as a community, we had a lot of discussion about the design/implementation of the Operator and how it should interact with the autoscaler.

This issue is to add the document that reflects the discussion that took place, with the conclusion of using a Microservice approach with separation of concern between the Life-cycle management (K8s Operator) and autoscaling decisions (Autoscaler).