Update README with citation (#591)

* Update README with citation and AI tools information

Added citation for research and details about Unity AI tools.

* Update README.md spacing

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: Marcus Sanatan <msanatan@gmail.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

README.md

@@ -212,6 +212,25 @@ Anonymous, privacy-focused telemetry (no code, no project names, no personal dat
 
 [![Star History Chart](https://api.star-history.com/svg?repos=CoplayDev/unity-mcp&type=Date)](https://www.star-history.com/#CoplayDev/unity-mcp&Date)
 
+<details>
+<summary><strong>Citation for Research</strong></summary>
+If you are working on research that is related to Unity-MCP, please cite us!
+
+```bibtex
+@inproceedings{10.1145/3757376.3771417,
+author = {Wu, Shutong and Barnett, Justin P.},
+title = {MCP-Unity: Protocol-Driven Framework for Interactive 3D Authoring},
+year = {2025},
+isbn = {9798400721366},
+publisher = {Association for Computing Machinery},
+address = {New York, NY, USA},
+url = {https://doi.org/10.1145/3757376.3771417},
+doi = {10.1145/3757376.3771417},
+series = {SA Technical Communications '25}
+}
+```
+</details>
+
 ## Unity AI Tools by Coplay
 
 Coplay offers 3 AI tools for Unity: