Simplify two doi urls [ci skip]

Author: eddelbuettel

README.md

@@ -13,9 +13,9 @@
 [![CRAN use](https://jangorecki.gitlab.io/rdeps/Rcpp/CRAN_usage.svg?sanitize=true)](https://cran.r-project.org/package=Rcpp)
 [![CRAN indirect](https://jangorecki.gitlab.io/rdeps/Rcpp/indirect_usage.svg?sanitize=true)](https://cran.r-project.org/package=Rcpp)
 [![BioConductor use](https://jangorecki.gitlab.io/rdeps/Rcpp/BioC_usage.svg?sanitize=true)](https://cran.r-project.org/package=Rcpp)
-[![JSS](https://img.shields.io/badge/JSS-10.18637%2Fjss.v040.i08-brightgreen)](https://dx.doi.org/10.18637/jss.v040.i08)
+[![JSS](https://img.shields.io/badge/JSS-10.18637%2Fjss.v040.i08-brightgreen)](https://doi.org/10.18637/jss.v040.i08)
 [![Springer useR!](https://img.shields.io/badge/Springer%20useR!-10.1007%2F978--1--4614--6868--4-brightgreen)](https://www.amazon.com/gp/product/1461468671/ref=as_li_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=1461468671&linkCode=as2&tag=rcpp-20&linkId=3P5LNUWOAQ2YMEJ6)
-[![TAS](https://img.shields.io/badge/TAS-10.1080%2F00031305.2017.1375990-brightgreen)](https://dx.doi.org/10.1080/00031305.2017.1375990)
+[![TAS](https://img.shields.io/badge/TAS-10.1080%2F00031305.2017.1375990-brightgreen)](https://doi.org/10.1080/00031305.2017.1375990)
 
 ### Synopsis