Update free-courses-en.md (#8393)

Added a C Programming course

courses/free-courses-en.md

@@ -268,6 +268,7 @@
 * [C Programming for Beginners](https://www.youtube.com/playlist?list=PL98qAXLA6aftD9ZlnjpLhdQAOFI8xIB6e) - Programiz
 * [C Programming Tutorial](https://www.youtube.com/playlist?list=PL_RGaFnxSHWoGzOXqtKeM71OLpvZbuU0P)
 * [C Programming Tutorial for Beginners](https://www.youtube.com/watch?v=KJgsSFOSQv0) - Mike Dane (freeCodeCamp)
+* [Learn C Programming](https://www.programiz.com/c-programming) - Programiz (HTML)
 * [Programming in C](https://www.youtube.com/playlist?list=PLdo5W4Nhv31a8UcMN9-35ghv8qyFWD9_S) - Jenny's lectures CS/IT NET&JRF 
 * [The Arduino Platform and C Programming](https://www.coursera.org/learn/arduino-platform)