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

---------

Co-authored-by: Mert Yanık <mert.yanik@lcwaikiki.com>
Co-authored-by: Steven Liu <59462357+stevhliu@users.noreply.github.com>

docs/source/tr/_toctree.yml

@@ -0,0 +1,4 @@
+- sections:
+  - local: index
+    title: 🤗 Transformers
+  title: Get started