docs: Coroutines guide: update URL (#4411)

Author: murfel

docs/topics/coroutines-guide.md

@@ -20,7 +20,7 @@ In order to use coroutines as well as follow the examples in this guide, you nee
 ## Table of contents
 
 * [Coroutines basics](coroutines-basics.md)
-* [Hands-on: Intro to coroutines and channels](https://play.kotlinlang.org/hands-on/Introduction%20to%20Coroutines%20and%20Channels)
+* [Tutorial: Intro to coroutines and channels](coroutines-and-channels.md)
 * [Cancellation and timeouts](cancellation-and-timeouts.md)
 * [Composing suspending functions](composing-suspending-functions.md)
 * [Coroutine context and dispatchers](coroutine-context-and-dispatchers.md)