Improve README

[UrekMaz]

The README is useful but a bit short for new users. Please add a few practical examples and a short deploy/troubleshooting section so people can get started faster.

What to do (small tasks)

Add 1 curl example showing how to upload a CSV file to POST /process/csv.
Add 1 short Python example showing how to call the JSON mode (requests + JSON body).
Add a short “Deploy on Render” subsection with the start command and required env vars (e.g. CSVAPI_EXPORT_DIR, CSVAPI_MAX_UPLOAD_MB).
Add a short Troubleshooting section with 3 tips: “No UI found”, “413 upload too large”, and “export directory/mount issues”.
Files to edit

README.md
Acceptance criteria

README contains the curl example and Python example.
README has a Deploy on Render section with the start command: python -m uvicorn main:app --host 0.0.0.0 --port $PORT --workers 2.
README has a Troubleshooting section covering the three tips above.

[harshit-sharma2005]

Hey @UrekMaz I would love to contribute to the issue. Please assign it to me.

[Hrishikesh-Dalal]

Assigned to you @harshit-sharma2005