Update README: license

README.md

@@ -85,4 +85,14 @@ Download the STIPLAR-eval dataset from [Link](https://huggingface.co/datasets/an
 
 ## License
 
-This project is licensed under the **Apache License 2.0**.
+### Dataset
+The dataset contained in this repository consists of web-crawled images originally
+distributed under the following open licenses: CC0, CC BY, CC BY-NC, and PDM.
+
+- Each image retains its original license, which is specified in the metadata.
+- For CC BY images, proper attribution to the original creator is required.
+- For CC BY-NC images, commercial use is not permitted.
+- For CC0 and PDM images, the content is in the public domain and may be freely used.
+
+The dataset curators do not claim ownership of the original images,
+only of the metadata and dataset organization, which are released under CC BY 4.0.