aws-replicator: add meaningful documentation / schema for config yaml

[chrisweight]

Currently, there are only a few very small examples of how to configure the aws-replicator extension via YAML. This makes it very hard to grok how to properly customise the extension.

It would be incredibly helpful to have something more comprehensive available as a reference.

For instance: Say I have a local SQS queue of dev-sqs-queue and I want to forward all requests to a remote staging-aws-queue - there is no easily available reference for this.