Add Course to free-courses-en.md (#9674)

courses/free-courses-en.md

@@ -175,6 +175,7 @@
 * [MIT's Design and Analysis of Algorithms (Spring 2015)](https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-046j-design-and-analysis-of-algorithms-spring-2015) - Erik Demaine, Srini Devadas, Nancy Lynch
 * [MIT's Introduction to Algorithms (Fall 2011)](http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-006-introduction-to-algorithms-fall-2011/)
 * [MIT's Introduction to Algorithms (SMA 5503) (Fall 2005)](https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-046j-introduction-to-algorithms-sma-5503-fall-2005) - Charles Leiserson, Erik Demaine
+* [MIT's Introduction to Algorithms (Spring 2020)](https://ocw.mit.edu/courses/6-006-introduction-to-algorithms-spring-2020/) - Erik Demaine, Jason Ku, Justin Solomon
 * [Online Java + DSA + Interview preparation course](https://www.youtube.com/playlist?list=PL9gnSGHSqcnr_DxHsP7AW9ftq0AtAyYqJ) - Kunal Kushwaha
 * [Princeton University Algorithms, Part 1](https://www.coursera.org/learn/algorithms-part1)
 * [Princeton University Algorithms, Part 2](https://www.coursera.org/learn/algorithms-part2)