Create example usage script for multi_agent_benchmark.py #21

Description:
Provide an example script that demonstrates how to run the multi_agent_benchmark.py module.

Steps:

• Create a new file under examples/ (e.g., examples/multi_agent_example.py)
• Show how to import and run multi_agent_benchmark
• Add simple usage instructions

Acceptance Criteria:

• Example runs without errors
• Example script is referenced in README.md