docs: add OpenTelemetry tracing example for SDK observability

[amankumar092]

Added a small documentation example showing how users can integrate OpenTelemetry tracing around Kubeflow SDK calls for better debugging and observability.

This aligns with improving SDK developer experience and monitoring workflows.

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[github-actions]

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[Copilot]

Pull request overview

This pull request adds a new "Observability and Tracing" section to the README documentation, providing users with guidance on integrating OpenTelemetry for monitoring and debugging Kubeflow SDK operations.

Changes:

• Added a new section titled "Observability and Tracing" documenting integration with OpenTelemetry
• Included a code example showing how to wrap SDK calls with OpenTelemetry tracing spans
• Positioned the section logically between "Local Development" and "Supported Kubeflow Projects"