Update tutorial docs (#15165)

* first draft of pipeline, autoclass, preprocess tutorials

* apply review feedback

* 🖍 apply feedback from patrick/niels

* 📝add output image to preprocessed image

* 🖍 apply feedback from patrick

docs/source/_toctree.yml

@@ -11,12 +11,16 @@
     title: Glossary
   title: Get started
 - sections:
+  - local: pipeline_tutorial
+    title: Pipelines for inference
+  - local: autoclass_tutorial
+    title: Load pretrained instances with an AutoClass
+  - local: preprocessing
+    title: Preprocess
   - local: task_summary
     title: Summary of the tasks
   - local: model_summary
     title: Summary of the models
-  - local: preprocessing
-    title: Preprocessing data
   - local: training
     title: Fine-tuning a pretrained model
   - local: accelerate
@@ -27,7 +31,7 @@
     title: Summary of the tokenizers
   - local: multilingual
     title: Multi-lingual models
-  title: "Using 🤗 Transformers"
+  title: Tutorials
 - sections:
   - local: examples
     title: Examples