[DOCS] Clarify that TF backend must be used to download test split of VOC datasets

[MLRadfys]

URL(s) with the issue

https://docs.voxel51.com/user_guide/dataset_zoo/datasets.html#dataset-zoo-voc-2012

Description of proposal (what needs changing)

Hi,

according to the documentation, VOC2012 and VOC2007 "test" splits are available in the tf backend. Unfortunately Iam not able to download the test split for the two datasets:

ValueError: Invalid split 'test'; supported values are ('train', 'validation')

As far as I have understood, the base class automatically chooses the backend for which the split exists?

Thanks in advance,

best regards,

M

Willingness to contribute

The FiftyOne Community encourages documentation contributions. Would you or another member of your organization be willing to contribute a fix for this documentation issue to the FiftyOne codebase?

• [ ] Yes. I can contribute a documentation fix independently
• [ ] Yes. I would be willing to contribute a documentation fix with guidance from the FiftyOne community
• [ x] No. I cannot contribute a documentation fix at this time