add citation readme

Author: quentinblampey

README.md

@@ -56,4 +56,23 @@ Check [our documentation](https://quentinblampey.github.io/spatialdata_xenium_ex
 
 ## Contributing
 
-This package is still in early development. Contributions are welcome (new issues, pull requests, ...).
+This package is still in early development. Contributions are welcome (new issues, pull requests, ...).
+
+## Cite us
+
+This library has been detailed in a more general article spatial omics analysis, see the [Sopa library](https://github.com/gustaveroussy/sopa).
+The latter article is not published yet, but you can cite our [preprint](https://www.biorxiv.org/content/10.1101/2023.12.22.571863v1):
+
+```txt
+@article {Blampey2023.12.22.571863,
+	author = {Quentin Blampey & Kevin Mulder et al.},
+	title = {Sopa: a technology-invariant pipeline for analyses of image-based spatial-omics},
+	elocation-id = {2023.12.22.571863},
+	year = {2023},
+	doi = {10.1101/2023.12.22.571863},
+	publisher = {Cold Spring Harbor Laboratory},
+	URL = {https://www.biorxiv.org/content/early/2023/12/23/2023.12.22.571863},
+	eprint = {https://www.biorxiv.org/content/early/2023/12/23/2023.12.22.571863.full.pdf},
+	journal = {bioRxiv}
+}
+```