docs: add workload safety note to README

[enoshdev]

Summary

Added a workload safety note to the Help Test KORA section in README.md as described in issue Krako-Labs#92. The note reminds contributors to use only synthetic or sanitized examples and avoid sensitive data.

Type of change

• Docs only

Verification

• Validation commands were run or marked not applicable.
• Claim hygiene checked.
• No unsupported production, API-cost, benchmark, broad workload, or energy claims added.
• No raw benchmark JSON artifacts committed.
• No local absolute paths introduced.
• No release, tag, package-version, or release-asset changes unless explicitly explicitly approved.

List commands run and results:

N/A - documentation only change