ktl-873 chore: support Dokka HTML customization (#239)

Author: nikpachoo

core/build.gradle.kts

@@ -347,6 +347,8 @@ val downloadWindowsZonesMapping by tasks.registering {
 }
 
 tasks.withType<AbstractDokkaLeafTask>().configureEach {
+    pluginsMapConfiguration.set(mapOf("org.jetbrains.dokka.base.DokkaBase" to """{ "templatesDir" : "${projectDir.toString().replace('\\', '/')}/dokka-templates" }"""))
+
     dokkaSourceSets.configureEach {
         // reportUndocumented.set(true) // much noisy output about `hashCode` and serializer encoders, decoders etc
         skipDeprecated.set(true)

core/dokka-templates/README.md

@@ -0,0 +1,12 @@
+# Dokka's template customization
+To provide unified navigation for all parts of [kotlinlang.org](https://kotlinlang.org/),
+the Kotlin Website Team uses this directory to place custom templates in this folder
+during the website build time on TeamCity.
+
+It is not practical to place these templates in the kotlinx-datetime repository because they change from time to time
+and aren't related to the library's release cycle.
+
+The folder is defined as a source for custom templates by the templatesDir property through Dokka's plugin configuration.
+
+[Here](https://kotlin.github.io/dokka/1.7.20-SNAPSHOT/user_guide/output-formats/html/#custom-html-pages), you can
+find more about the customization of Dokka's HTML output.