Generation doc (#6470)

* Generation doc

* MBartForConditionalGeneration (#6441)

* add MBartForConditionalGeneration

* style

* rebase and fixes

* add mbart test in TEST_FILES_WITH_NO_COMMON_TESTS

* fix docs

* don't ignore mbart

* doc

* fix mbart fairseq link

* put mbart before bart

* apply doc suggestions

* Use hash to clean the test dirs (#6475)

* Use hash to clean the test dirs

* Use hash to clean the test dirs

* Use hash to clean the test dirs

* fix

* [EncoderDecoder] Add Cross Attention for GPT2 (#6415)

* add cross attention layers for gpt2

* make gpt2 cross attention work

* finish bert2gpt2

* add explicit comments

* remove attention mask since not yet supported

* revert attn mask in pipeline

* Update src/transformers/modeling_gpt2.py

Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>

* Update src/transformers/modeling_encoder_decoder.py

Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>

Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>

* Sort unique_no_split_tokens to make it deterministic (#6461)

* change unique_no_split_tokens's type to set

* use sorted list instead of set

* style

* Import accuracy_score (#6480)

* Apply suggestions from code review

Co-authored-by: Lysandre Debut <lysandre@huggingface.co>

* Address comments

* Styling

* Generation doc

* Apply suggestions from code review

Co-authored-by: Lysandre Debut <lysandre@huggingface.co>

* Address comments

* Styling

Co-authored-by: Suraj Patil <surajp815@gmail.com>
Co-authored-by: Kevin Canwen Xu <canwenxu@126.com>
Co-authored-by: Patrick von Platen <patrick.v.platen@gmail.com>
Co-authored-by: Quentin Lhoest <42851186+lhoestq@users.noreply.github.com>
Co-authored-by: gijswijnholds <gijswijnholds@gmail.com>
Co-authored-by: Lysandre Debut <lysandre@huggingface.co>

docs/source/main_classes/model.rst

@@ -12,7 +12,9 @@ are common among all the models to:
 - prune the attention heads of the model.
 
 The other methods that are common to each model are defined in :class:`~transformers.modeling_utils.ModuleUtilsMixin`
-(for the PyTorch models) and :class:`~transformers.modeling_tf_utils.TFModuleUtilsMixin` (for the TensorFlow models).
+(for the PyTorch models) and :class:`~transformers.modeling_tf_utils.TFModuleUtilsMixin` (for the TensorFlow models) or
+for text generation, :class:`~transformers.generation_utils.GenerationMixin` (for the PyTorch models) and
+:class:`~transformers.generation_tf_utils.TFGenerationMixin` (for the TensorFlow models)
 
 
 ``PreTrainedModel``
@@ -46,4 +48,8 @@ The other methods that are common to each model are defined in :class:`~transfor
 Generative models
 ~~~~~~~~~~~~~~~~~
 
-Coming soon
+.. autoclass:: transformers.generation_utils.GenerationMixin
+    :members:
+
+.. autoclass:: transformers.generation_tf_utils.TFGenerationMixin
+    :members: