chore: Create CITATION.cff

[HsiangNianian]

Dear KANs team, thank you very much for your research on the KANs algorithm.

This PullRequest mainly adds the CITATION.cff file, which will add a Cite this repository button in the repo's properties column. For details about the key-value pairs of CITATION.cff, please refer to about-citation-files.

@article{Liu_KAN_Kolmogorov-Arnold_Networks_2024,
author = {Liu, Ziming and Wang, Yixuan and Vaidya, Sachin and Ruehle, Fabian and Halverson, James and Solja{\v{c}}i{\'c}, Marin and Hou, Thomas Y and Tegmark, Max},
doi = {10.48550/arXiv.2404.19756},
journal = {arXiv preprint arXiv:2404.19756},
title = {{KAN: Kolmogorov-Arnold Networks}},
url = {https://github.com/KindXiaoming/pykan},
year = {2024}
}