README: remove link to Genetics journal

Author: kbroman

README.md

@@ -56,7 +56,7 @@ To cite R/qtl2 in publications, use:
 > Yandell BS, Churchill GA (2019)
 > R/qtl2: software for mapping quantitative trait loci with
 > high-dimensional data and multi-parent populations.
-> [Genetics](https://academic.oup.com/genetics) 211:495-502
+> Genetics 211:495-502
 > [doi:10.1534/genetics.118.301595](https://doi.org/10.1534/genetics.118.301595)
 
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