translated citation

waiting for actual publication to updated x's 
closes #54

CITATION

@@ -1,6 +1,8 @@
-Please cite as:
+Por favor cite como:
 
-Thomas Wright and Naupaka Zimmerman (eds): "Software Carpentry: R for
-Reproducible Scientific Analysis."  Version 2016.06, June 2016,
-https://github.com/swcarpentry/r-novice-gapminder,
-10.5281/zenodo.57520.
+Rayna Harris, Veronica Jimenez, Silvana Pereyra, 
+and Heladia Saldago (eds), xx authors:
+“Software Carpentry: R para Análisis Científicos Reproducibles",
+The Carpentries, Version xxx, April 2018,
+https://github.com/swcarpentry/r-novice-gapminder-es,
+xx.xxxx/zendod.xxxx.