fix: simplify setup instructions (#5412)

Author: murfel

docs/topics/js/js-get-started.md

@@ -21,7 +21,7 @@ Community or Ultimate edition of [IntelliJ IDEA](https://www.jetbrains.com/idea/
 ### Set up the environment
 
 1. Download and install the latest version of [IntelliJ IDEA](https://www.jetbrains.com/idea/).
-2. [Set up your environment for Kotlin Multiplatform development](https://kotlinlang.org/docs/multiplatform/quickstart.html#set-up-the-environment).
+2. Install the [Kotlin Multiplatform IDE plugin](https://plugins.jetbrains.com/plugin/14936-kotlin-multiplatform) (not to be confused with the Kotlin Multiplatform Gradle plugin).
 
 ### Create your project
 
@@ -434,4 +434,4 @@ IntelliJ IDEA displays the error message in the **Build** pane.
 * Learn how to [debug Kotlin/JS applications](js-debugging.md).
 * Learn how to [write and run tests with Kotlin/JS](js-running-tests.md).
 * Learn how to [write Gradle build scripts for real-life Kotlin/JS projects](https://kotlinlang.org/docs/multiplatform/multiplatform-dsl-reference.html).
-* Read more about the [Gradle build system](gradle.md).
+* Read more about the [Gradle build system](gradle.md).