docs: update README with correct Uvicorn command for src structure

[vinay22573]

📌 Description

This PR updates the README to include the correct Uvicorn command when the project follows a src/ structure. This helps prevent ImportErrors and ensures users can run the application smoothly.

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🔹 Changes Made

✅ Added a note in the README to clarify the correct way to start the FastAPI server when main.py is inside src/.
✅ Provided the correct Uvicorn command:

uvicorn src.main:app --reload

✅ Checklist

• I have read the Contribution Guidelines.
• I have tested these changes locally.
• I have updated the documentation (README).
• The code follows the project's documentation and formatting standards.

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