Update stale prototype references (#2189)

Summary:
Missed a couple of spots in https://github.com/pytorch/audio/issues/2187.

Pull Request resolved: https://github.com/pytorch/audio/pull/2189

Reviewed By: carolineechen, nateanl, mthrok

Differential Revision: D33926342

Pulled By: hwangjeff

fbshipit-source-id: e1324c0fe8f9be90ad3143d19cd61c3d53f02b06

docs/source/index.rst

@@ -58,8 +58,6 @@ Prototype API References
 
    prototype
    prototype.ctc_decoder
-   prototype.models
-   prototype.pipelines
 
 Getting Started
 ---------------

examples/asr/librispeech_emformer_rnnt/pipeline_demo.py

@@ -3,7 +3,7 @@ from argparse import ArgumentParser
 
 import torch
 import torchaudio
-from torchaudio.prototype.pipelines import EMFORMER_RNNT_BASE_LIBRISPEECH
+from torchaudio.pipelines import EMFORMER_RNNT_BASE_LIBRISPEECH
 
 
 def cli_main():