[repo] Update Dokka to 1.8.20 version

This release also fixes some problems with KGP-api documentation
publication.

buildSrc/build.gradle.kts

@@ -98,7 +98,7 @@ dependencies {
     implementation(kotlin("stdlib", embeddedKotlinVersion))
     implementation("org.jetbrains.kotlin:kotlin-build-gradle-plugin:${kotlinBuildProperties.buildGradlePluginVersion}")
     implementation("com.gradle.publish:plugin-publish-plugin:1.0.0")
-    implementation("org.jetbrains.dokka:dokka-gradle-plugin:1.8.10")
+    implementation("org.jetbrains.dokka:dokka-gradle-plugin:1.8.20")
 
     implementation("org.spdx:spdx-gradle-plugin:0.1.0-dev-7")
 

buildSrc/src/main/kotlin/GradleCommon.kt

@@ -698,7 +698,7 @@ fun Project.configureDokkaPublication(
 
             project.dependencies {
                 // Version is required due to https://github.com/Kotlin/dokka/issues/2812
-                "dokkaPlugin"("org.jetbrains.dokka:versioning-plugin:$dokkaVersioningPluginVersion")
+                "dokkaHtmlPlugin"("org.jetbrains.dokka:versioning-plugin:$dokkaVersioningPluginVersion")
             }
 
             tasks.register<DokkaTask>("dokkaKotlinlangDocumentation") {