Update free-courses-en.md (#10822)

courses/free-courses-en.md

@@ -1484,6 +1484,7 @@
 
 ### R
 
+* [Introduction to R](https://www.datacamp.com/courses/free-introduction-to-r) - DataCamp
 * [R Basics - R Programming Language Introduction](https://www.udemy.com/course/r-basics/) - R-Tutorials Training (Udemy)
 * [R Programming](https://www.coursera.org/course/rprog)
 * [R Programming Tutorial](https://www.youtube.com/watch?v=_V8eKsto3Ug) - Barton Poulson (freeCodeCamp)