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* Add LayoutLMForSequenceClassification and integration tests

Improve docs

Add LayoutLM notebook to list of community notebooks

* Make style & quality

* Address comments by @sgugger, @patrickvonplaten and @LysandreJik

* Fix rebase with master

* Reformat in one line

* Improve code examples as requested by @patrickvonplaten
Co-authored-by: Lysandre <lysandre.debut@reseau.eseo.fr>
Co-authored-by: Lysandre Debut <lysandre@huggingface.co>