Add object detection processing tutorial

[nateraw]

The following adds a quick guide on how to process object detection datasets with albumentations.

[HuggingFaceDocBuilderDev]

The documentation is not available anymore as the PR was closed or merged.

[lhoestq]

Love it, thanks ! This section in image_process was about demonstrating how to do data augmentation. Maybe it can be worth separating the "how to do image classif/obj detection" from it, and have on dedicated page per task ? WDYT @stevhliu ?

[stevhliu]

Great idea! Now that we have more than one task, it makes sense to separate image classification and object detection so it'll be easier for users to follow.

[nateraw]

@lhoestq do we want to do that in this PR, or should we merge it and let @stevhliu reorganize separately?

[stevhliu]

Looks fantastic, thanks for adding this guide (I left mostly small style nits)!

I think this will be a great template for other guides we plan to add to this section. Also, happy to reorganize separately and update the image classification guide to be more like this one :)