Translate index.mdx (to ES) and add Spanish models to quicktour.mdx examples (#16685)

* Change nits in Spanish for quicktour.mdx

- Add tasks names in English too.
- Fix small nits in Spanish

* Translate index.mdx to Spanish

* Translate body of index.
* Translated the compatible models list (not the papers´ names). Since this should not be updated manually, I can come back to the original text.

* Add models and a  dataset for Spanish in the code exmaples

* Replaced the English models to Spanish versions.

* Add index to _toctree.yml and fix Spanish

* Fix double ““ error

* Change negative example in ASR example

* make style

* Debug style in quicktour.mdx

docs/source/es/_toctree.yml

@@ -1,6 +1,8 @@
-- sections: 
+- sections:
+  - local: index
+    title: 🤗 Transformers
   - local: quicktour
-    title: Quick tour
+    title: Tour rápido
   - local: installation
     title: Instalación
   title: Empezar