[doc] Prometheus metrics tutorial needs an update

[cijothomas]

Package

None

Is your feature request related to a problem?

No. https://github.com/open-telemetry/opentelemetry-dotnet/tree/main/docs/metrics/getting-started-prometheus-grafana#install-and-run-prometheus doc is outdated as Prometheus now supports OTLP as a standard feature, not experimental. The feature still requires opt-in, but flag names have changed.

What is the expected behavior?

Update the doc to reflect newest Prometheus.

Which alternative solutions or features have you considered?

None.

Additional context

Screenshot of my working setup. (I use it with other language tutorials. Don't have bandwidth to try and fix the tutorial in this repo at the moment)
We can briefly cover Resource -> Dimension conversion also, as Prometheus now natively support those.!