Fix mkdocs documentation leading to non-stable versions (#2870)

Fixes #2869

mkdocs/build.gradle.kts

@@ -1,3 +1,15 @@
+import org.jetbrains.dokkaVersionType
+import org.jetbrains.DokkaVersionType
+
 plugins {
     id("ru.vyarus.mkdocs") version "2.3.0"
 }
+
+if (dokkaVersionType != DokkaVersionType.RELEASE) {
+    // Do not generate the root index.html file with the redirect
+    // to a non-release version, otherwise GitHub pages based documentation
+    // will always lead to the non-stable documentation.
+    // For more details, see https://github.com/Kotlin/dokka/issues/2869.
+    // For configuration details, see https://xvik.github.io/gradle-mkdocs-plugin/3.0.0/examples/#simple-multi-version.
+    mkdocs.publish.rootRedirect = false
+}