[Docs] ONNX inference on ONNXRUNTIME

[zakharchik-me]

📚 The doc issue

I've converted my pth model (Faster_rcnn_r50) to onnx
It does work clearly as backend onnx using mmdet api
Unfortunately, can't get such results uisng only ONNXRUNTIME and CV2
Any suggestions?

Suggest a potential alternative/fix

No response