Issues with documentation generations

[mthrok]

make html command issues the following warnings;

/torchaudio/torchaudio/models/wav2letter.py:docstring of torchaudio.models.Wav2Letter:4: WARNING: Inline interpreted text or phrase reference start-string without end-string.
o/torchaudio/torchaudio/transforms.py:docstring of torchaudio.transforms.GriffinLim:4: WARNING: Footnote [1] is not referenced.
/torchaudio/torchaudio/transforms.py:docstring of torchaudio.transforms.GriffinLim:8: WARNING: Footnote [2] is not referenced.
/torchaudio/torchaudio/transforms.py:docstring of torchaudio.transforms.GriffinLim:13: WARNING: Footnote [3] is not referenced.
/torchaudio/docs/source/models.rst: WARNING: document isn't included in any toctree