Update README with citation and contribution note

Added equal contribution note and updated citation.

Author: lciernik

README.md

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 A gene expression signature scoring Python package.  
 
 This repository accompanies the work: Laure Ciernik*, Agnieszka Kraft*, Joséphine Yates, Florian Barkmann, and 
-Valentina Boeva, “ANS: Adjusted Neighborhood Scoring to improve gene signature-based cell annotation in single-cell RNA-seq data”. doi: [https://doi.org/10.1101/2023.09.20.558114](https://doi.org/10.1101/2023.09.20.558114)
+Valentina Boeva, “ANS: Adjusted Neighborhood Scoring to improve gene signature-based cell annotation in single-cell RNA-seq data”. Genome Research doi: 10.1101/gr.280926.125
+
+*\*Equal contribution*
 
 *Note: This repository is in the experimental stage. Changes to the API may appear.*