[Docs] Spanish translation of task_summary.md (#28844)

* Add task_summary to es/_toctree.yml

* Add task_summary.md to docs/es

* Change title of task_summary.md

* Translate firsts paragraphs

* Translate middle paragraphs

* Translte the rest of the doc

* Edit firts paragraph

docs/source/es/_toctree.yml

@@ -80,6 +80,8 @@
     title: Filosofía
   - local: glossary
     title: Glosario
+  - local: task_summary
+    title: Lo que 🤗 Transformers puede hacer
   - local: pad_truncation
     title: Relleno y truncamiento
   - local: bertology