Fix TORCH_HOME environment variable in docs (#4843)

* Fix TORCH_HOME environment variable in docs

* Update docs with torch.hub

Updated the reference for loading a model to `torch.hub`.
Co-authored-by: Nicolas Hug <contact@nicolas-hug.com>
Co-authored-by: Nicolas Hug <contact@nicolas-hug.com>

docs/source/models.rst

@@ -127,8 +127,8 @@ These can be constructed by passing ``pretrained=True``:
     regnet_x_32gf = models.regnet_x_32gf(pretrained=True)
 
 Instancing a pre-trained model will download its weights to a cache directory.
-This directory can be set using the `TORCH_MODEL_ZOO` environment variable. See
-:func:`torch.utils.model_zoo.load_url` for details.
+This directory can be set using the `TORCH_HOME` environment variable. See
+:func:`torch.hub.load_state_dict_from_url` for details.
 
 Some models use modules which have different training and evaluation
 behavior, such as batch normalization. To switch between these modes, use