docs: Adding Opik to OpenTelemetry

[vincentkoc]

Comet's Opik is a leading open-source LLM telemetry, evaluation and optimization platform. Opik has native support for Pipecat with Opik, and this PR adds working examples.

We are also working on an audio version of our Opik Optimizer SDK (dedicated agent/prompt/instruction optimization SDK) which we are working on example with Pipecat and will be making a subsequent PR. Please reach out if you have any questions or issues.

[markbackman]

We're happy to add Opik, but to do so, you should first add an example to pipecat-examples:
https://github.com/pipecat-ai/pipecat-examples/tree/main/open-telemetry

[vincentkoc]

@markbackman raised pipecat-ai/pipecat-examples#71

[markbackman]

Rather than add a new section, can you extend the HTTP exporter section? I would suggest the following:

### HTTP OTLP Exporter (for Langfuse, Opik, etc.)

```python
from opentelemetry.exporter.otlp.proto.http.trace_exporter import OTLPSpanExporter

exporter = OTLPSpanExporter(
    # Configure with environment variables:
    # OTEL_EXPORTER_OTLP_ENDPOINT
    # OTEL_EXPORTER_OTLP_HEADERS
)

See HTTP OTLP Exporter examples:

Bot example with Langfuse Bot example with Opik ```

Then, in your example's README, add all the information you need!

[vincentkoc]

@markbackman any updates?