docs(kotlin-script): remove metadata, rewrite (#20192)

Co-authored-by: Rhys Arkins <rhys@arkins.net>

lib/modules/manager/kotlin-script/readme.md

----
-title: Kotlin Script dependency versions
-description: Kotlin Script dependency versions support in Renovate
----
-
 Renovate supports upgrading dependencies in [Kotlin Script](https://github.com/Kotlin/KEEP/blob/master/proposals/scripting-support.md) files.
-These are self-contained scripts where one can write Kotlin code with JVM backend, and compilation happens when the
-scripts are ran. For example:
+Read the [Kotlin Script docs](https://kotlinlang.org/docs/custom-script-deps-tutorial.html) to learn more.
+For example:
 
 ```kotlin
 #!/usr/bin/env kotlin
@@ -19,9 +14,10 @@ println("Hello world!")
 // ...
 ```
 
-By default, Renovate scans files only with `.main.kts` extension and not `.kts`, to avoid ambiguity with Gradle config
-files that have `.gradle.kts` extension. As there are cases where just `.kts` extension or no extension is used,
-Renovate can be [configured](https://docs.renovatebot.com/configuration-options/) to scan also these:
+By default, Renovate only scans files with the `.main.kts` extension and not `.kts`.
+This way Renovate avoids ambiguity with Gradle config files that use the `.gradle.kts` extension.
+
+If you want to manage other Kotlin Script files, you may use the `fileMatch` config option to let Renovate update these files:
 
 ```json
 {