Add ninja workshop on sending application metrics

[billg-splunk]

Is your feature request related to a problem? Please describe.
Customer would like a workshop on sending custom metrics. Maybe we can build a short example using this otel example:
https://github.com/open-telemetry/opentelemetry-java-examples/tree/main/metrics

Describe the solution you'd like
Workshop that can demonstrate how to send application metrics.

Describe alternatives you've considered
NONE: Looking for options, if one exists already then this isn't needed.

Additional context
Reported by @bryan-splunk.