Update free-courses-en.md (#11647)

courses/free-courses-en.md

@@ -1620,6 +1620,7 @@
 
 ### Rust
 
+* [Complete Rust Marathon](https://www.youtube.com/watch?v=joCFbTJt0o0&t=20s) - Harkirat Singh
 * [Comprehensive Rust](https://google.github.io/comprehensive-rust/index.html) - Google
 * [Intro to Rust](https://www.youtube.com/playlist?list=PLJbE2Yu2zumDF6BX6_RdPisRVHgzV02NW) - Tensor Programming
 * [Learn Rust from scratch](https://www.educative.io/courses/learn-rust-from-scratch) - Educative.io