Tokenizers: ability to load from model subfolder (#8586)

* <small>tiny typo</small>

* Tokenizers: ability to load from model subfolder

* use subfolder for local files as well

* Uniformize model shortcut name => model id

* from s3 => from huggingface.co

Co-authored-by: Quentin Lhoest <lhoest.q@gmail.com>

examples/rag/finetune.sh

@@ -7,7 +7,7 @@ export PYTHONPATH="../":"${PYTHONPATH}"
 python examples/rag/finetune.py \
     --data_dir $DATA_DIR \
     --output_dir $OUTPUT_DIR \
-    --model_name_or_path $MODLE_NAME_OR_PATH \
+    --model_name_or_path $MODEL_NAME_OR_PATH \
     --model_type rag_sequence \
     --fp16 \
     --gpus 8 \