PegasusForConditionalGeneration (torch version) (#6340)

Co-authored-by: Jingqing  Zhang <jingqing.zhang15@imperial.ac.uk>

docs/source/index.rst

@@ -124,7 +124,9 @@ conversion utilities for the following models:
 22. `DPR <https://github.com/facebookresearch/DPR>`_ (from Facebook) released with the paper `Dense Passage Retrieval
     for Open-Domain Question Answering <https://arxiv.org/abs/2004.04906>`_ by Vladimir Karpukhin, Barlas Oğuz, Sewon
     Min, Patrick Lewis, Ledell Wu, Sergey Edunov, Danqi Chen, and Wen-tau Yih.
-23. `Other community models <https://huggingface.co/models>`_, contributed by the `community
+23. `Pegasus <https://github.com/google-research/pegasus>`_ (from Google) released with the paper `PEGASUS: Pre-training with Extracted Gap-sentences for Abstractive Summarization
+    <https://arxiv.org/abs/1912.08777>`_ by Jingqing Zhang, Yao Zhao, Mohammad Saleh and Peter J. Liu.
+24. `Other community models <https://huggingface.co/models>`_, contributed by the `community
     <https://huggingface.co/users>`_.
 
 .. toctree::
@@ -205,6 +207,7 @@ conversion utilities for the following models:
     model_doc/retribert
     model_doc/mobilebert
     model_doc/dpr
+    model_doc/pegasus
     internal/modeling_utils
     internal/tokenization_utils
-    internal/pipelines_utils
+    internal/pipelines_utils