[Docs] No preview images for Det3DLocalVisualizer

[toshi-k]

Branch

main branch https://mmdetection3d.readthedocs.io/en/latest/

📚 The doc issue

I recently tried to use Det3DLocalVisualizer and noticed that the resulting images were not displayed in the documentation samples.
https://mmdetection3d.readthedocs.io/en/latest/user_guides/visualization.html

I think it's because there are no images in the resources directory. Can someone fix it?
https://github.com/open-mmlab/mmdetection3d/tree/fe25f7a51d36e3702f961e198894580d83c4387b/resources

Suggest a potential alternative/fix

Add and relikng resulting images.