added a complete course on linear algebra for machine learning (#10862)

courses/free-courses-en.md

@@ -1224,6 +1224,7 @@
 * [Intro to Machine Learning using Microsoft Azure](https://www.udacity.com/course/introduction-to-machine-learning-using-microsoft-azure--ud00333) - Microsoft (Udacity)
 * [Intro to Self-Driving Cars Nanodegree](https://www.udacity.com/course/intro-to-self-driving-cars--nd113) - Cezanne Camacho, Andrew Paster, Anthony Navarro, Tarin Ziyaee, et al. (Udacity)
 * [Introduction to Machine Learning](https://openlearninglibrary.mit.edu/courses/course-v1:MITx+6.036+1T2019/about) - MIT Open Learning Library
+* [Linear Algebra for Machine Learning](https://www.youtube.com/playlist?list=PLRDl2inPrWQW1QSWhBU0ki-jq_uElkh2a) - Jon Krohn
 * [Machine Learning](https://www.sololearn.com/Course/machine-learning) (SoloLearn) *(account required)*
 * [Machine Learning](https://youtube.com/playlist?list=PL7T06JEc5PF5Vuz1U7lEEaFPOExDbKVEh) - Nerd's Lesson
 * [Machine Learning](https://youtube.com/playlist?list=PLblh5JKOoLUICTaGLRoHQDuF_7q2GfuJF) - StatQuest with Josh Starmer