[i18n-en] Translating docs to Japanese

Hi! Let's bring the documentation to all the Japanese-speaking community 🌐 Who would want to translate? Please follow the 🤗 [TRANSLATING guide](https://github.com/huggingface/transformers/blob/main/docs/TRANSLATING.md). Here is a list of the files ready for translation. Let us know in this issue if you'd like to translate any, and we'll add your name to the list. Some notes: * Please translate using an informal tone (imagine you are talking with a friend about transformers 🤗). * Please translate in a gender-neutral way. * Add your translations to the folder called `ja` inside the [source folder](https://github.com/huggingface/transformers/tree/main/docs/source). * Register your translation in `ja/_toctree.yml`; please follow the order of the [English version](https://github.com/huggingface/transformers/blob/main/docs/source/en/_toctree.yml). * Once you're finished, open a pull request and tag this issue by including #issue-number in the description, where issue-number is the number of this issue. Please ping @stevhliu and @MKhalusova for review. * 🙋 If you'd like others to help you with the translation, you can also post in the 🤗 [forums](https://discuss.huggingface.co/). ## Model doc section - [ ] [deit.md](https://github.com/huggingface/transformers/blob/main/docs/source/en/model_doc/deit.md) #28302 - [ ] [deplot.md](https://github.com/huggingface/transformers/blob/main/docs/source/en/model_doc/deplot.md) #28302 - [ ] [deta.md](https://github.com/huggingface/transformers/blob/main/docs/source/en/model_doc/deta.md) #28302 - [ ] [detr.md](https://github.com/huggingface/transformers/blob/main/docs/source/en/model_doc/detr.md) #28302 - [ ] [dialogpt.md](https://github.com/huggingface/transformers/blob/main/docs/source/en/model_doc/dialogpt.md) - [ ] [dinat.md](https://github.com/huggingface/transformers/blob/main/docs/source/en/model_doc/dinat.md) - [ ] [dinov2.md](https://github.com/huggingface/transformers/blob/main/docs/source/en/model_doc/dinov2.md)#29272 - …