README.md

`arhat` Config

Though there are multiple sample configurations, they follow the same configuration model and have same configuration fields.

agent - defines arhat's behavior
runtime - defines the way to communicate with container runtime
- different runtime has different requirements for configuration fields, please refer to these configuration samples for details
connectivity - defines the way to communicate with aranya
- requires its own configuration depending on the arhat type
  - arhat-{}-grpc requires .connectivity.grpc_config
  - arhat-{}-mqtt requires .connectivity.mqtt_config