Clarifies what the dice example demonstrates

[n9te9]

Background

Dice example README didn't clearly state what users can learn from this example.
As a result, first-time users may be unsure about the learning focus of the dice example.

What

This change adds a short description to clarify what this example demonstrates.

[linux-foundation-easycla]

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• ✅ login: n9te9 / name: n9te9 (7e03eec)

[dmathieu]

Your statement isn't accurate. The otelhttp handler will do tracing too.

[n9te9]

@dmathieu
You're absolutely right - the otelhttp handler does create spans and performs tracing.
What I wanted to clarify in the README is not that tracing is absent, the example's primary learning focus, from a first-time user's perspective, is metrics instrumentation (for example, the custom dice.rolls metrics and exemplars).
The change is intended to make the learning intent of the example clearer, rather than to imply tracing is not involved.