Update README.md

Publication I/README.md

@@ -10,6 +10,6 @@ L. Prieto Santamaría, E. P. García del Valle, M. Zanin, G. S. Hernández Chan,
 
 :point_right: Go to [supplementary information](https://medal.ctb.upm.es/internal/gitlab/lprieto/phd-thesis-luciaprietosantamaria/blob/master/Publication%20I/SM%20-%20Publication%20I.pdf)
 
-The broad methodology used in this publications is summarized in the following figure:
+The broad methodology used in this publication is summarized in the following figure:
 
 <img src="./Pub I methodology.svg">
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