added yaml section and course video (#8499)

courses/free-courses-en.md

@@ -94,6 +94,7 @@
     * [Deno](#deno)
 * [Verilog / VHDL / SystemVerilog](#verilog--vhdl--systemverilog)
 * [Web Development](#web-development)
+* [YAML](#yaml)
 
 
 ### 0 - MOOC
@@ -1291,3 +1292,8 @@
 * [Web Development Tutorials for Beginners](https://www.youtube.com/playlist?list=PLoYCgNOIyGAB_8_iq1cL8MVeun7cB6eNc) - LearnCode.academy
 * [Web Information Retrieval](https://www.youtube.com/playlist?list=PLAQopGWlIcya-9yzQ8c8UtPOuCv0mFZkr) - L. Becchetti, A. Vitaletti (University of Sapienza Rome)
 * [Web Programming](https://open.cs.uwaterloo.ca/web-programming/) - Centre for Education in Math and Computing (University of Waterloo)
+
+
+### YAML
+
+* [Complete YAML Course - Beginner to Advanced for DevOps and more!](https://www.youtube.com/watch?v=IA90BTozdow) - Kunal Kushwaha