Add: task guide for zero shot object detection
This PR adds a task guide for zero-shot object detection. Unlike other task guides, there is no fine-tuning and complex preprocessing of custom data. However, the task illustrates different ways of inferencing with OWL-ViT, such as using the pipeline, manual inference with text queries, manual inference for a batch of examples, and image-guided object detection. The task guide is based on [this notebook](https://github.com/huggingface/notebooks/blob/main/examples/zeroshot_object_detection_with_owlvit.ipynb) with some additions (e.g. pipeline example) and some modifications.
Images are in this PR https://huggingface.co/datasets/huggingface/documentation-images/discussions/49<|||||>_The documentation is not available anymore as the PR was closed or merged._<|||||>> Nice work, thanks for adding this! I especially like the brief intro to the OWL-ViT model. Maybe we can embed one of the OWL-ViT demos (like this [one](https://huggingface.co/spaces/adirik/OWL-ViT)) directly on the page so users can play with it?

Thanks for the suggestion! I embedded demo :)