Update README with Numbat-multiome reference

Added reference to the Numbat-multiome paper in the README.

Author: teng-gao

README.md

@@ -23,6 +23,7 @@ Numbat does not require paired DNA or genotype data and operates solely on the d
 
 ## Numbat-multiome
 Numbat was later extended to multi-modality (single-cell RNA and ATAC) data. Check out the [vignette](https://kharchenkolab.github.io/numbat/articles/numbat-multiome.html) and paper below:
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 > [Ruitong Li, Jean-Baptiste Alberge, Tina Keshavarzian, Junko Tsuji, Johan Gustafsson, Mahshid Rahmat, Elizabeth D Lightbody, Stephanie L Deng, Santiago Riviero, Mendy Miller, F Naz Cemre Kalayci, Adrian Wiestner, Clare Sun, Mathieu Lupien, Irene Ghobrial, Erin Parry, Teng Gao, Gad Getz. Numbat-multiome: inferring copy number variations by combining RNA and chromatin accessibility information from single-cell data. Briefings in Bioinformatics (2025).](https://academic.oup.com/bib/article/26/5/bbaf516/8290422)