Update README.md

Disclaimer: [illian64](https://huggingface.co/illian64) who was not involved in this research, converted the original models to CTranslate2 optimized model and wrote the contents of this model card based on google/madlad400-10b-mt.

Convert params:
`ct2-transformers-converter --model google/madlad400-10b-mt --quantization bfloat16 --output_dir madlad400-10b-mt-bfloat16`

README.md

@@ -426,4 +426,6 @@ base_model:
 - google/madlad400-10b-mt
 pipeline_tag: translation
 library_name: transformers
+tags:
+- text2text-generation
 ---