Added docs for reference scripts (#4574)

docs/source/index.rst

@@ -41,9 +41,10 @@ architectures, and common image transformations for computer vision.
 
 .. toctree::
    :maxdepth: 1
-   :caption: Examples
+   :caption: Examples and training references
 
    auto_examples/index
+   training_references
 
 .. automodule:: torchvision
    :members:

docs/source/models.rst

+.. _models:
+
 torchvision.models
 ##################
 

docs/source/training_references.rst

+Training references
+===================
+
+On top of the many models, datasets, and image transforms, Torchvision also
+provides training reference scripts. These are the scripts that we use to train
+the :ref:`models <models>` which are then available with pre-trained weights.
+
+These scripts are not part of the core package and are instead available `on
+GitHub <https://github.com/pytorch/vision/tree/main/references>`_. We currently
+provide references for
+`classification <https://github.com/pytorch/vision/tree/main/references/classification>`_,
+`detection <https://github.com/pytorch/vision/tree/main/references/detection>`_,
+`segmentation <https://github.com/pytorch/vision/tree/main/references/segmentation>`_,
+`similarity learning <https://github.com/pytorch/vision/tree/main/references/similarity>`_,
+and `video classification <https://github.com/pytorch/vision/tree/main/references/video_classification>`_.
+
+While these scripts are largely stable, they do not offer backward compatibility
+guarantees.
+
+In general, these scripts rely on the latest (not yet released) pytorch version
+or the latest torchvision version. This means that to use them, **you might need
+to install the latest pytorch and torchvision versions**, with e.g.::
+
+    conda install pytorch torchvision -c pytorch-nightly
+
+If you need to rely on an older stable version of pytorch or torchvision, e.g.
+torchvision 0.10, then it's safer to use the scripts from that corresponding
+release on GitHub, namely
+https://github.com/pytorch/vision/tree/v0.10.0/references.