Added translation of index.mdx to Portuguese Issue #16824 (#17565)

* Added translation of installation.mdx to Portuguese, as well
as default templates of _toctree.yml and _config.py

* [ build_documentation.yml ] - Updated doc_builder to build
documentation in Portuguese.
[ pipeline_tutorial.mdx ] - Created translation for the pipeline_tutorial.mdx.

* [ build_pr_documentation.yml ] - Added pt language to pr_documentation builder.

[ pipeline_tutorial.mdx ] - Grammar changes.

* [ accelerate.mdx ] - Translated to Portuguese the acceleration tutorial.

* [ multilingual.mdx ] - Added portuguese translation for multilingual tutorial.

[ training.mdx ] - Added portuguese translation for training tutorial.

* [ preprocessing.mdx ] - WIP

* Update _toctree.yml

* Adding Pré-processamento to _toctree.yml

* Update accelerate.mdx

* Nits and eliminate preprocessing file while it is ready

* [ index.mdx ] - Translated to Portuguese the index apresentation page.

* [ docs/source/pt ] - Updated _toctree.yml to match newest translations.

* Fix build_pr_documentation.yml

* Fix index nits

* nits in _toctree

Co-authored-by: Omar U. Espejel <espejelomar@gmail.com>

docs/source/pt/_toctree.yml

@@ -1,9 +1,11 @@
 - sections:
+  - local: index
+    title: 🤗 Transformers
   - local: quicktour
     title: Tour rápido
   - local: installation
     title: Instalação
-  title: Iniciar
+  title: Início
 - sections:
   - local: pipeline_tutorial
     title: Pipelines para inferência