Translate index.md to Turkish (#27093)
* Add index.md for tukish language
* Fix index.md (huggingface/transformers#27088)
* Add 'tr' to additional files
* Update docs/source/tr/_toctree.yml
Co-authored-by: Steven Liu <59462357+stevhliu@users.noreply.github.com>
* Update index.md
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Co-authored-by: Mert Yanık <mert.yanik@lcwaikiki.com>
Co-authored-by: Steven Liu <59462357+stevhliu@users.noreply.github.com>
