Add index for Rust lang, and two free courses in `free-courses-ko.md` (#6287)

* Add index for Rust lang, and two free courses in free-courses-ko.md

* Fix by alphabetical order

* Fix spacing between langs

* Fix the header size

* Fix type of resource

courses/free-courses-ko.md

@@ -29,6 +29,7 @@
 * [Raspberry Pi](#raspberry-pi)
 * [Reinforced Learning](#reinforced-learning)
 * [Ruby](#ruby)
+* [Rust](#rust)
 * [Security](#security)
 * [Spring](#spring)
 * [Swift](#swift)
@@ -217,6 +218,12 @@
 * [Ruby coin](https://www.youtube.com/playlist?list=PLEBQPmkNcLCIE9ERi4k_nUkGgJoBizx6s)
 
 
+### Rust
+
+* [Team Jupeter - Rust by Examples](https://www.youtube.com/playlist?list=PLlSZlNj22M7SywLz61Wseh6iVGWRrtH76) - Team Jupeter (유튜브 채널) 
+* [Team Jupeter - The Rust Programming Language](https://www.youtube.com/playlist?list=PLlSZlNj22M7TBqclhEMkXFabaDCmds0mg) - Team Jupeter (유튜브 채널) 
+
+
 ### Security
 
 * [시스템 해킹 강좌](https://www.youtube.com/playlist?list=PLRx0vPvlEmdAXwJnNtKIVeC27UmwljRYA)