Update coroutines-guide.md (#3012)

* Update coroutines-guide.md

"kotlinx.coroutines guide" Google search first result still leads here and it would be nice to guide people directly to kotlinlang

Co-authored-by: dkhalanskyjb <52952525+dkhalanskyjb@users.noreply.github.com>

Author: qwwdfsad

coroutines-guide.md

@@ -1,14 +1,3 @@
 The main coroutines guide has moved to the [docs folder](docs/topics/coroutines-guide.md) and split up into smaller documents.
 
-## Table of contents
-
-<!--- TOC_REF docs/topics/coroutines-basics.md -->
-<!--- TOC_REF docs/topics/cancellation-and-timeouts.md -->
-<!--- TOC_REF docs/topics/composing-suspending-functions.md -->
-<!--- TOC_REF docs/topics/coroutine-context-and-dispatchers.md -->
-<!--- TOC_REF docs/topics/flow.md -->
-<!--- TOC_REF docs/topics/channels.md -->
-<!--- TOC_REF docs/topics/exception-handling.md -->
-<!--- TOC_REF docs/topics/shared-mutable-state-and-concurrency.md -->
-<!--- TOC_REF docs/topics/select-expression.md -->
-<!--- END -->
+It is recommended to read the guide on the [kotlinlang website](https://kotlinlang.org/docs/coroutines-guide.html), with proper HTML formatting and runnable samples.