[docs] Remove Hiera from AUDIO MODELS in docs (#35544)

Remove Hiera from AUDIO MODELS

Hiera is a visual model and should not appear in audio model...

Author: ADAning

docs/source/en/_toctree.yml

@@ -760,8 +760,6 @@
         title: dac
       - local: model_doc/encodec
         title: EnCodec
-      - local: model_doc/hiera
-        title: Hiera
       - local: model_doc/hubert
         title: Hubert
       - local: model_doc/mctct