Update README.md

I've found this course very interesting and well taught by Brian Yu and David J. Malan (Harvard University).
For me is a great introductory course with challenging exercises.
Course's Syllabus: 
0. Search
1. Knowledge
2. Uncertainty
3. Optimization
4. Learning
5. Neural Networks
6. Language

README.md

@@ -244,6 +244,7 @@ Courses
 ------------------------------
 
 ### Artificial Intelligence
+- [CS50 - Introduction to Artificial Intelligence with Python (and Machine Learning), Harvard OCW](https://cs50.harvard.edu/ai/2020/)
 - [CS 188 - Introduction to Artificial Intelligence, UC Berkeley - Spring 2015](http://www.infocobuild.com/education/audio-video-courses/computer-science/cs188-spring2015-berkeley.html)
 - [6.034 Artificial Intelligence, MIT OCW](https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-034-artificial-intelligence-fall-2010/lecture-videos/)
 - [CS221: Artificial Intelligence: Principles and Techniques - Autumn 2019 - Stanford University](https://www.youtube.com/playlist?list=PLoROMvodv4rO1NB9TD4iUZ3qghGEGtqNX)