233 task add readmemd file to stress testing

[Aravinda-HWK]

📌 Description

This PR is to update the README.md file for load testing.

• Closes [TASK] Add README.md file to stress testing #233

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🔍 Changes Made

• Add a README.md file to run stress testing

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✅ Checklist (Email System)

• Core services tested (SMTP, IMAP, mail storage, end-to-end delivery)
• Security & compliance verified (auth via Thunder IDP, TLS, DKIM/SPF/DMARC, spam/virus filtering)
• Configuration & deployment checked (configs generated, Docker/Compose updated)
• Reliability confirmed (error handling, logging, monitoring)
• Documentation & usage notes updated (README, deployment, API)

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🧪 Testing Instructions

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📷 Screenshots / Logs (if applicable)

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⚠️ Notes for Reviewers