docs: Clarify metric collection methods for NTH modes by younsl · Pull Request #1084 · aws/aws-node-termination-handler

@younsl

* Explained how Prometheus metric collection differs between IMDS and Queue modes.

* Added a warning about serviceMonitor and podMonitor being Prometheus Operator resources.

* Updated Queue mode to include two methods for metrics collection: using serviceMonitor with the Prometheus Operator or adding the aws-node-termination-handler service in `scrape_configs`.

* Provided an example `scrape_configs` for Prometheus in the Helm chart.

* Updated IMDS mode to mention podMonitor for metrics collection.