Add `language_bcp47` tag (#4753)

* fix ms_terms

* fix ted_talks_iwslt

* move tags to language_bcp47

* fix bad codes

* add language_details and language_bcp47 in DatasetMetadata

* more fixes

* fix wiki_dpr

Commit from https://github.com/huggingface/datasets/commit/aa48a29d1304167dff37cef0ed7542f29376ee2d

README.md

@@ -8,17 +8,17 @@ task_ids:
 - language-modeling
 - masked-language-modeling
 language:
+- bn
+- en
+- gu
 - hi
-- te
-- ta
 - ml
-- gu
-- ur
-- bn
-- or
 - mr
+- or
 - pa
-- en
+- ta
+- te
+- ur
 annotations_creators:
 - no-annotation
 source_datasets: