change rcpp link to new site

Author: jjallaire

about.md

@@ -7,7 +7,7 @@ title: About
 
 The *Rcpp Gallery* is a collection of community contributed articles and code
 examples that illustrate techniques for programming with
-[Rcpp](http://dirk.eddelbuettel.com/code/rcpp.html). The goal is to provide a
+[Rcpp](http://www.rcpp.org/). The goal is to provide a
 forum for easy sharing of technical insights and methods of work. We hope
 this helps both beginners to get started with Rcpp as well as advanced users
 to glean insights from seeing how others use Rcpp to solve more challenging