Split docs on modality (#18205)

* update

* 🖍 add missing files

* 📝 add nested sections

* 🖍 align titles with tasks

* oops

* remove quotes from titles

docs/source/en/_toctree.yml

@@ -21,12 +21,27 @@
     title: Share a model
   title: Tutorials
 - sections:
-  - local: fast_tokenizers
-    title: Use tokenizers from 🤗 Tokenizers
+  - sections:
     - local: create_a_model
       title: Create a custom architecture
     - local: custom_models
       title: Sharing custom models
+    - local: run_scripts
+      title: Train with a script
+    - local: sagemaker
+      title: Run training on Amazon SageMaker
+    - local: converting_tensorflow_models
+      title: Converting TensorFlow Checkpoints
+    - local: serialization
+      title: Export 🤗 Transformers models
+    - local: troubleshooting
+      title: Troubleshoot
+    title: General usage
+  - sections:
+    - local: fast_tokenizers
+      title: Use tokenizers from 🤗 Tokenizers
+    - local: multilingual
+      title: Inference for multilingual models
     - sections:
       - local: tasks/sequence_classification
         title: Text classification
@@ -42,23 +57,19 @@
         title: Summarization
       - local: tasks/multiple_choice
         title: Multiple choice
+      title: Task guides
+      isExpanded: false
+    title: Natural Language Processing
+  - sections:
     - local: tasks/audio_classification
       title: Audio classification
     - local: tasks/asr
       title: Automatic speech recognition
+    title: Audio
+  - sections:
     - local: tasks/image_classification
       title: Image classification
-    title: Fine-tune for downstream tasks
-  - local: run_scripts
-    title: Train with a script
-  - local: sagemaker
-    title: Run training on Amazon SageMaker
-  - local: multilingual
-    title: Inference for multilingual models
-  - local: converting_tensorflow_models
-    title: Converting TensorFlow Checkpoints
-  - local: serialization
-    title: Export 🤗 Transformers models
+    title: Computer Vision
   - sections:
     - local: performance
       title: Overview
@@ -84,31 +95,31 @@
       title: Inference on Specialized Hardware
     - local: perf_hardware
       title: Custom hardware for training
-    title: Performance and scalability
     - local: big_models
       title: Instantiating a big model
-  - local: benchmarks
-    title: Benchmarks
-  - local: migration
-    title: Migrating from previous packages
-  - local: troubleshooting
-    title: Troubleshoot
     - local: debugging
       title: Debugging
-  - local: notebooks
-    title: 🤗 Transformers Notebooks
-  - local: community
-    title: Community
+    title: Performance and scalability
+  - sections:
     - local: contributing
       title: How to contribute to transformers?
     - local: add_new_model
       title: How to add a model to 🤗 Transformers?
     - local: add_new_pipeline
-    title: How to create a custom pipeline?
+      title: How to add a pipeline to 🤗 Transformers?
     - local: testing
       title: Testing
     - local: pr_checks
       title: Checks on a Pull Request
+    title: Contribute
+  - local: notebooks
+    title: 🤗 Transformers Notebooks
+  - local: community
+    title: Community resources
+  - local: benchmarks
+    title: Benchmarks
+  - local: migration
+    title: Migrating from previous packages
   title: How-to guides
 - sections:
   - local: philosophy