Update README.md to include ISO codes for available languages

ISO Source:

Glottolog: https://glottolog.org/resource/languoid/id/lush1249
Wiki: https://en.wikipedia.org/wiki/Mizo_language
Hugging Face: https://huggingface.co/languages

README.md

@@ -28,6 +28,9 @@ configs:
     path: data/train-*
   - split: test
     path: data/test-*
+language:
+- en
+- lus
 ---
 
 # Mizo-English Parallel Sentences