Update README.md (#638)

* Update README.md

Update citation.

* Update README.md

README.md

@@ -138,12 +138,13 @@ Please follow our [short guide](https://github.com/blackjax-devs/blackjax/blob/m
 To cite this repository:
 
 ```
-@software{blackjax2020github,
-  author = {Cabezas, Alberto, Lao, Junpeng, and Louf, R\'emi},
-  title = {{B}lackjax: A sampling library for {JAX}},
-  url = {http://github.com/blackjax-devs/blackjax},
-  version = {<insert current release tag>},
-  year = {2023},
+@misc{cabezas2024blackjax,
+      title={BlackJAX: Composable {B}ayesian inference in {JAX}},
+      author={Alberto Cabezas and Adrien Corenflos and Junpeng Lao and Rémi Louf},
+      year={2024},
+      eprint={2402.10797},
+      archivePrefix={arXiv},
+      primaryClass={cs.MS}
 }
 ```
 In the above bibtex entry, names are in alphabetical order, the version number should be the last tag on the `main` branch.