Change license info

Update the license info according to the original IBM Research database.
Add the link to the original dataset in README.md

README.md

@@ -4,7 +4,7 @@ annotations_creators:
 language:
 - en
 license:
-- other
+- apache-2.0
 pretty_name: Watsonx Docs Document Type Classification
 size_categories:
 - n<1K
@@ -89,5 +89,4 @@ interpreted as belonging to the opposite binary class.
 The final subset contains 400 examples, sampled with random seed `42` after
 manual correction and filtering.
 
-License follows the terms of the source dataset `ibm-research/watsonxDocsQA`.
-Please refer to the original dataset for licensing details.
+This dataset is derived from [ibm-research/watsonxDocsQA](https://huggingface.co/datasets/ibm-research/watsonxDocsQA), which is licensed under Apache 2.0. This dataset inherits the same license.