[marian] Automate Tatoeba-Challenge conversion (#7709)

scripts/tatoeba/README.md

@@ -0,0 +1,44 @@
+Setup transformers following instructions in README.md, (I would fork first).
+```bash
+git clone git@github.com:huggingface/transformers.git
+cd transformers
+pip install -e .
+pip install pandas
+```
+
+Get required metadata
+```
+curl https://cdn-datasets.huggingface.co/language_codes/language-codes-3b2.csv  > language-codes-3b2.csv
+curl https://cdn-datasets.huggingface.co/language_codes/iso-639-3.csv > iso-639-3.csv
+```
+
+Install Tatoeba-Challenge repo inside transformers
+```bash
+git clone git@github.com:Helsinki-NLP/Tatoeba-Challenge.git
+```
+
+To convert a few models, call the conversion script from command line:
+```bash
+python src/transformers/convert_marian_tatoeba_to_pytorch.py --models heb-eng eng-heb --save_dir converted
+```
+
+To convert lots of models you can pass your list of Tatoeba model names to `resolver.convert_models` in a python client or script.
+
+```python
+from transformers.convert_marian_tatoeba_to_pytorch import TatoebaConverter
+resolver = TatoebaConverter(save_dir='converted')
+resolver.convert_models(['heb-eng', 'eng-heb'])
+```
+
+
+### Upload converted models
+```bash
+cd converted
+transformers-cli login
+for FILE in *; do transformers-cli upload $FILE; done
+```
+
+
+### Modifications
+- To change naming logic, change the code near `os.rename`. The model card creation code may also need to change.
+- To change model card content, you must modify `TatoebaCodeResolver.write_model_card`