Publish a JSON schema of the config

Having a JSON schema for the config format would be a lot more convenient than the current format of the docs: https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/CloudWatch-Agent-Configuration-File-Details.html

It would have the following advantages:
1. Probably easier to read than the docs IMO
2. It's a better specified and completely unambiguous documentation format
3. If we're generating config with our own code we could validate that it's correct before passing it to CloudWatch Agent
4. We could generate TypeScript types etc. from a JSON schema

The issue names no repository files or tests; start by locating the CloudWatch Agent configuration definition and comparing it with the linked configuration documentation. Determine the schema's required coverage and publication location, then verify that the published schema represents the documented format and supports config validation.

Written by the indexing model from the issue text.