Update online learning resources section with the reactive programming course

Author: julienrf

learn.md

@@ -11,8 +11,9 @@ redirect_from:
 ## Online Courses from EPFL
 
 The following courses are available for free. They teach you the main features of the Scala language and introduce you
-to functional programming. They are published on both [Coursera](https://www.coursera.org) and an EPFL-hosted Open edX
-instance at [courseware.epfl.ch](https://courseware.epfl.ch/).
+to functional programming. They are published on both [Coursera](https://www.coursera.org) and edX (either on an
+EPFL-hosted Open edX instance at [courseware.epfl.ch](https://courseware.epfl.ch/), or on
+[www.edx.org](https://www.edx.org)).
 
  * Functional Programming in Scala Specialization (on [Coursera](https://www.coursera.org/specializations/scala)).
    The Specialization provides a hands-on introduction to functional programming using Scala. You can access the courses
@@ -26,11 +27,13 @@ instance at [courseware.epfl.ch](https://courseware.epfl.ch/).
       [Open edX](https://courseware.epfl.ch/courses/course-v1:EPFL+parprog1+2018_T1/about)),
     * Big Data Analysis with Scala and Spark ([Coursera](https://www.coursera.org/learn/scala-spark-big-data) and
       [Open edX](https://courseware.epfl.ch/courses/course-v1:EPFL+scala-spark-big-data+2018-T1/about)),
-    * Functional Programming in Scala Capstone ([Coursera](https://www.coursera.org/learn/scala-capstone) only).
+    * Functional Programming in Scala Capstone ([Coursera](https://www.coursera.org/learn/scala-capstone) only),
+ * Programming Reactive Systems ([edX](https://www.edx.org/course/programming-reactive-systems) only).
 
-Note : On Coursera there is a paid version available. The only difference between the free and the paid version is that
-you get a certificate of completion from Coursera on the paid version. You can learn more about coursera certificates in
-[this help document](https://learner.coursera.help/hc/en-us/articles/209819053-Get-a-Course-Certificate).
+Note : On Coursera and edX, there is a paid version available. The only difference with the free version is that
+the paid version delivers a certificate of completion. Learn more about
+[Coursera certificates](https://learner.coursera.help/hc/en-us/articles/209819053-Get-a-Course-Certificate) or
+[edX certificates](https://support.edx.org/hc/en-us/categories/115002269627-Certificates).
 
 ## Dr.Mark C Lewis's Lectures from Trinity University