Add new token classification example

examples/README.md

@@ -37,7 +37,7 @@ git checkout tags/v3.4.0
 |---|---|:---:|:---:|:---:|:---:|
 | [**`language-modeling`**](https://github.com/huggingface/transformers/tree/master/examples/language-modeling)       | Raw text        | ✅ | -  | ✅ | [![Open In Colab](https://colab.research.google.com/assets/colab-badge.svg)](https://colab.research.google.com/github/huggingface/blog/blob/master/notebooks/01_how_to_train.ipynb)
 | [**`text-classification`**](https://github.com/huggingface/transformers/tree/master/examples/text-classification)   | GLUE, XNLI      | ✅ | ✅ | ✅ | [![Open In Colab](https://colab.research.google.com/assets/colab-badge.svg)](https://github.com/huggingface/notebooks/blob/master/examples/text_classification.ipynb)
-| [**`token-classification`**](https://github.com/huggingface/transformers/tree/master/examples/token-classification) | CoNLL NER       | ✅ | ✅ | - | -
+| [**`token-classification`**](https://github.com/huggingface/transformers/tree/master/examples/token-classification) | CoNLL NER       | ✅ | ✅ | ✅ | -
 | [**`multiple-choice`**](https://github.com/huggingface/transformers/tree/master/examples/multiple-choice)           | SWAG, RACE, ARC | ✅ | ✅ | - | [![Open In Colab](https://colab.research.google.com/assets/colab-badge.svg)](https://colab.research.google.com/github/ViktorAlm/notebooks/blob/master/MPC_GPU_Demo_for_TF_and_PT.ipynb)
 | [**`question-answering`**](https://github.com/huggingface/transformers/tree/master/examples/question-answering)     | SQuAD           | ✅ | ✅ | - | -
 | [**`text-generation`**](https://github.com/huggingface/transformers/tree/master/examples/text-generation)           | -               | n/a | n/a | - | [![Open In Colab](https://colab.research.google.com/assets/colab-badge.svg)](https://colab.research.google.com/github/huggingface/blog/blob/master/notebooks/02_how_to_generate.ipynb)

examples/test_examples.py

@@ -44,7 +44,7 @@
     import run_generation
     import run_glue
     import run_mlm
-    import run_ner_new as run_ner
+    import run_ner
     import run_pl_glue
     import run_squad
 

examples/token-classification/README.md

@@ -1,6 +1,38 @@
-## Named Entity Recognition
+## Token classification
 
-Based on the scripts [`run_ner.py`](https://github.com/huggingface/transformers/blob/master/examples/token-classification/run_ner.py) for Pytorch and
+Fine-tuning the library models for token classification task such as Named Entity Recognition (NER) or Parts-of-speech
+tagging (POS). The main scrip `run_ner.py` leverages the 🤗 Datasets library and the Trainer API. You can easily
+customize it to your needs if you need extra processing on your datasets.
+
+It will either run on a datasets hosted on our [hub](https://huggingface.co/datasets) or with your own text files for
+training and validation.
+
+The following example fine-tunes BERT on CoNLL-2003:
+
+```bash
+python run_ner.py \
+  --model_name_or_path bert-base-uncased \
+  --dataset_name conll2003 \
+  --output_dir /tmp/test-ner \
+  --do_train \
+  --do_eval
+```
+
+To run on your own training and validation files, use the following command:
+
+```bash
+python run_ner.py \
+  --model_name_or_path bert-base-uncased \
+  --train_file path_to_train_file \
+  --validation_file path_to_validation_file \
+  --output_dir /tmp/test-ner \
+  --do_train \
+  --do_eval
+```
+
+## Old version of the script
+
+Based on the scripts [`run_ner_old.py`](https://github.com/huggingface/transformers/blob/master/examples/token-classification/run_ner_old.py) for Pytorch and
 [`run_tf_ner.py`](https://github.com/huggingface/transformers/blob/master/examples/token-classification/run_tf_ner.py) for Tensorflow 2.
 
 The following examples are covered in this section:
@@ -69,7 +101,7 @@ export SEED=1
 To start training, just run:
 
 ```bash
-python3 run_ner.py --data_dir ./ \
+python3 run_ner_old.py --data_dir ./ \
 --labels ./labels.txt \
 --model_name_or_path $BERT_MODEL \
 --output_dir $OUTPUT_DIR \