README: license section and dataset citations

Adds a **License** and a **Citation** section to the Space README.

- **License:** the P-Bench code stays Apache 2.0. The benchmark prompts and third-party data in `data/` keep their original licenses:
- OneIG-Bench prompts: CC BY-NC 4.0.
- Qwen-Image-Bench and VBench-2.0 prompts: Apache 2.0.
- Arena and Artificial Analysis leaderboard CSVs: the source's terms.

The section also says the prompts are copied verbatim, that P-Bench uses a selection of each benchmark with its own prompt IDs, and that Elo comes from Datapoint and Rapidata.
- **Citation:** the P-Bench entry plus the official BibTeX for OneIG-Bench (arXiv 2506.07977), Qwen-Image-Bench (arXiv 2605.28091) and VBench-2.0 (arXiv 2503.21755).
- The YAML `license: apache-2.0` is unchanged: it describes the code, and the README text covers the data.

**To check before merging:**
- The Arena row has no link yet. Please add the URL of the leaderboard `data/arena_ai_text_to_image_leaderboard.csv` comes from.
- Separate follow-up: credit the datasets in the app UI as well (the About tab, and next to the sample prompts).

README only, no code changes.

README.md

@@ -30,6 +30,67 @@ include only models with the required score and price or timing. Image-to-video
 sample media is not included in these exports.
 Rapidata Elo comes directly from these exports.
 
+## License
+
+The P-Bench code (the Gradio app, `app.py`, `ui.py`, `model_display.py`) is
+released under the [Apache License 2.0](https://www.apache.org/licenses/LICENSE-2.0).
+
+The benchmark prompts and third-party data in `data/` are **not** covered by
+that license. They keep the license or terms of their original source:
+
+| Data in this Space | Source | License / terms |
+| --- | --- | --- |
+| `data/oneig_combined/prompts.jsonl`: 299 OneIG-Bench prompts (anime, human and object alignment) | [OneIG-Bench](https://huggingface.co/datasets/OneIG-Bench/OneIG-Bench) (Chang et al., 2025) | [CC BY-NC 4.0](https://creativecommons.org/licenses/by-nc/4.0/) |
+| `data/qwen_image_bench_combined/prompts.jsonl`: 100 Qwen-Image-Bench prompts | [Qwen-Image-Bench](https://huggingface.co/datasets/Qwen/Qwen-Image-Bench) (Li et al., 2026) | [Apache 2.0](https://www.apache.org/licenses/LICENSE-2.0) |
+| `data/video_generation_combined/prompts.jsonl`: 90 VBench-2.0 prompts | [VBench-2.0](https://github.com/Vchitect/VBench/tree/master/VBench-2.0) (Zheng et al., 2025) | [Apache 2.0](https://github.com/Vchitect/VBench/blob/master/LICENSE) |
+| `data/arena_ai_text_to_image_leaderboard.csv` | Arena text-to-image leaderboard | the source's terms of use |
+| `data/artificial_analysis_text_to_image_leaderboard.csv` | [Artificial Analysis](https://artificialanalysis.ai/) text-to-image arena | the source's terms of use |
+
+The OneIG-Bench, Qwen-Image-Bench and VBench-2.0 prompts are copied verbatim.
+P-Bench uses a selection of each benchmark and adds its own prompt IDs. The
+generated images and videos come from the listed models. Human preference
+scores (Elo) were collected by Pruna AI through Datapoint and Rapidata.
+
+Because the OneIG-Bench prompts are licensed for non-commercial use only
+(CC BY-NC 4.0), any reuse of `data/oneig_combined/` must follow that license.
+
+## Citation
+
+If you use P-Bench, please cite it together with the benchmarks whose prompts it uses:
+
+```bibtex
+@misc{P-Bench,
+    title={P-Bench: A Leaderboard for Text-to-Image Models},
+    author={PrunaAI},
+    year={2026},
+    howpublished={\url{https://huggingface.co/spaces/PrunaAI/P-Bench}}
+}
+
+@article{chang2025oneig,
+    title={OneIG-Bench: Omni-dimensional Nuanced Evaluation for Image Generation},
+    author={Jingjing Chang and Yixiao Fang and Peng Xing and Shuhan Wu and Wei Cheng and Rui Wang and Xianfang Zeng and Gang Yu and Hai-Bao Chen},
+    journal={arXiv preprint arXiv:2506.07977},
+    year={2025}
+}
+
+@misc{li2026qwenimagebenchgenerationcreationtexttoimage,
+    title={Qwen-Image-Bench: From Generation to Creation in Text-to-Image Evaluation},
+    author={Niantong Li and Guangzheng Hu and Weixu Qiao and Ying Ba and Qichen Hong and Shijun Shen and Jinlin Wang and Fan Zhou and Jianye Kang and Xin Shang and Ziyi He and Wei Wang and Dalin Li and Jiahao Li and Jie Zhang and Kaiyuan Gao and Kun Yan and Lihan Jiang and Ningyuan Tang and Shengming Yin and Tianhe Wu and Xiao Xu and Xiaoyue Chen and Yuxiang Chen and Yan Shu and Yanran Zhang and Yilei Chen and Yixian Xu and Zekai Zhang and Zhendong Wang and Zihao Liu and Zikai Zhou and Hongzhu Shi and Yi Wang and Bing Zhao and Hu Wei and Lin Qu and Chenfei Wu},
+    year={2026},
+    eprint={2605.28091},
+    archivePrefix={arXiv},
+    primaryClass={cs.CV},
+    url={https://arxiv.org/abs/2605.28091}
+}
+
+@article{zheng2025vbench2,
+    title={{VBench-2.0}: Advancing Video Generation Benchmark Suite for Intrinsic Faithfulness},
+    author={Zheng, Dian and Huang, Ziqi and Liu, Hongbo and Zou, Kai and He, Yinan and Zhang, Fan and Zhang, Yuanhan and He, Jingwen and Zheng, Wei-Shi and Qiao, Yu and Liu, Ziwei},
+    journal={arXiv preprint arXiv:2503.21755},
+    year={2025}
+}
+```
+
 ## Run locally
 
 From the repo root: