Update datasets document (#2029)

Summary:
- Remove unnecessary content list
- Remove legacy description

Pull Request resolved: https://github.com/pytorch/audio/pull/2029

Reviewed By: carolineechen

Differential Revision: D32629917

Pulled By: mthrok

fbshipit-source-id: bc9a9366c681bcf8b74907c2a6459c73fb6a7424

docs/source/datasets.rst

@@ -15,15 +15,6 @@ For example: ::
                                               shuffle=True,
                                               num_workers=args.nThreads)
 
-The following datasets are available:
-
-.. contents:: Datasets
-    :local:
-
-All the datasets have almost similar API. They all have two common arguments:
-``transform`` and  ``target_transform`` to transform the input and target respectively.
-
-
 .. currentmodule:: torchaudio.datasets