Added Len Greski to list of community contributors.

Author: lgreski

about.md

@@ -19,8 +19,9 @@ The [Data Science Specialization](https://www.coursera.org/specialization/jhudat
 - [Kevin Markham](http://www.dataschool.io/)
 - Derek Franks
 - David Hood
+- [Leonard Greski](https://github.com/lgreski)
 - Michael Sachs
 - Allan Inocêncio de Souza Costa
 - [stepds](https://github.com/stepds)
 - Bastiaan Quast
-- [Xing Su](http://sux13.github.io/DataScienceSpCourseNotes/)
+- [Xing Su](http://sux13.github.io/DataScienceSpCourseNotes/)