note on Gradle Settings (#4095)

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Update docs based on
[feedback](kotest/kotest-intellij-plugin#294)

---------

Co-authored-by: Benoit Liessens <ebl@melexis.com>
Co-authored-by: Sam <sam@sksamuel.com>

documentation/docs/intellij/index.md

@@ -34,7 +34,10 @@ If you execute a test, then that test and all nested tests will be executed.
 
 ![gutter_icon_picture](../images/gutter_run.png)
 
-
+:::note
+For Gradle based projects: to run tests with the KoTest runner ensure your project's Gradle Settings are set to run tests with IntelliJ, not Gradle:
+![gradle_settings_picture](../images/gradle-settings.png)
+:::
 
 ## Duplicated Test Highlighting
 

documentation/versioned_docs/version-5.9/intellij/index.md

@@ -34,7 +34,10 @@ If you execute a test, then that test and all nested tests will be executed.
 
 ![gutter_icon_picture](../images/gutter_run.png)
 
-
+:::note
+For Gradle based projects: to run tests with the KoTest runner ensure your project's Gradle Settings are set to run tests with IntelliJ, not Gradle:
+![gradle_settings_picture](../images/gradle-settings.png)
+:::
 
 ## Duplicated Test Highlighting