added a 'last commit' badge

Author: eddelbuettel

ChangeLog

@@ -1,3 +1,7 @@
+2020-08-16  Dirk Eddelbuettel  <edd@debian.org>
+
+	* README.md: Add JSS badge
+
 2020-03-29  Dirk Eddelbuettel  <edd@debian.org>
 
 	* README.md: Added commit badge, edited

README.md

@@ -11,6 +11,8 @@
 [![CRAN use](https://jangorecki.gitlab.io/rdeps/RcppEigen/CRAN_usage.svg?sanitize=true)](https://cran.r-project.org/package=RcppEigen)
 [![BioConductor use](https://jangorecki.gitlab.io/rdeps/RcppEigen/BioC_usage.svg?sanitize=true)](https://cran.r-project.org/package=RcppEigen)
 [![StackOverflow](https://img.shields.io/badge/stackoverflow-rcpp-orange.svg)](https://stackoverflow.com/questions/tagged/rcpp)
+[![JSS](https://img.shields.io/badge/JSS-10.18637%2Fjss.v052.i05-brightgreen)](https://dx.doi.org/10.18637/jss.v052.i05)
+
 
 ### Synopsis