[Gradle] Update info about versioning

 ^KT-73076 Fixed

Author: Tapchicoma

libraries/tools/gradle/documentation/Readme.md

@@ -5,6 +5,9 @@ This project assembles API reference for Kotlin Gradle plugins to publish it to
 ### Configuration
 
 - `build/templates` dir is used for Kotlinlang website templates. Currently, they should be put there manually.
+- `build/documentation/kotlinlangOld` directory is used for previously generated documentation.
+  Inside the structure of subdirectories 
+should follow [this specification](https://github.com/Kotlin/dokka/tree/1.9.20/dokka-subprojects/plugin-versioning#directory-structure).
 
 ### Assembling
 

repo/gradle-build-conventions/gradle-plugins-documentation/src/main/kotlin/gradle-plugins-documentation.gradle.kts

@@ -71,6 +71,8 @@ tasks.register<org.jetbrains.dokka.gradle.DokkaMultiModuleTask>("dokkaKotlinlang
         "org.jetbrains.dokka.base.DokkaBase",
         "{ \"templatesDir\": \"${unzipTemplates.map { it.destinationDir }.get().also { it.mkdirs() }}\" }"
     )
+
+    // Documentation: https://github.com/Kotlin/dokka/tree/1.9.20/dokka-subprojects/plugin-versioning
     pluginsMapConfiguration.put(
         "org.jetbrains.dokka.versioning.VersioningPlugin",
         documentationExtension.documentationOldVersions.map { olderVersionsDir ->