Adopt `:autosummary:` in `torchaudio.datasets` module doc (#2692)

Summary:
* Introduce the mini-index at `torchaudio.datasets` page.
* Standardize the format of return type docstring.

https://output.circle-artifacts.com/output/job/989328b2-0270-4958-b577-19cf749af3fd/artifacts/0/docs/datasets.html

<img width="936" alt="Screen Shot 2022-09-21 at 6 56 52 PM" src="https://user-images.githubusercontent.com/855818/191475141-a97f2bea-705f-49bc-8c34-6ec869e76793.png">

https://output.circle-artifacts.com/output/job/989328b2-0270-4958-b577-19cf749af3fd/artifacts/0/docs/generated/torchaudio.datasets.CMUDict.html#torchaudio.datasets.CMUDict

<img width="1069" alt="Screen Shot 2022-09-21 at 6 57 32 PM" src="https://user-images.githubusercontent.com/855818/191475293-e3302528-27ea-4212-9c12-fd6d900fdf3e.png">

Pull Request resolved: https://github.com/pytorch/audio/pull/2692

Reviewed By: carolineechen

Differential Revision: D39687463

Pulled By: mthrok

fbshipit-source-id: 4175fc15388817d2fe76206188618dd1576281df

torchaudio/datasets/yesno.py

@@ -19,7 +19,7 @@ _RELEASE_CONFIGS = {
 
 
 class YESNO(Dataset):
-    """Create a Dataset for *YesNo* :cite:`YesNo`.
+    """*YesNo* :cite:`YesNo` dataset.
 
     Args:
         root (str or Path): Path to the directory where the dataset is found or downloaded.
@@ -72,7 +72,14 @@ class YESNO(Dataset):
             n (int): The index of the sample to be loaded
 
         Returns:
-            (Tensor, int, List[int]): ``(waveform, sample_rate, labels)``
+            Tuple of the following items;
+
+            Tensor:
+                Waveform
+            int:
+                Sample rate
+            List[int]:
+                labels
         """
         fileid = self._walker[n]
         item = self._load_item(fileid, self._path)