Merge pull request #1027 from levibostian/r-succinctly

Add R Succinctly book.

free-programming-books.md

@@ -1472,6 +1472,7 @@ See also [TeX](#tex)
 * [The R Inferno](http://www.burns-stat.com/pages/Tutor/R_inferno.pdf) (PDF) - Patrick Burns
 * [The R Language](http://stat.ethz.ch/R-manual/R-patched/doc/html/)
 * [The R Manuals](http://cran.r-project.org/manuals.html)
+* [R Succinctly, Syncfusion](http://www.syncfusion.com/resources/techportal/ebooks/rsuccinctly) (PDF, Kindle) *(Just fill the fields with any values)*
 
 
 ###Racket