ktl-695 chore: support Dokka HTML customization (#3388)

diff --git a/build.gradle b/build.gradle
index 4d6af16..ba6d5c1 100644
--- a/build.gradle
+++ b/build.gradle
@@ -355,3 +355,7 @@
                 }
             }
 }
+
+tasks.named("dokkaHtmlMultiModule") {
+    pluginsMapConfiguration.set(["org.jetbrains.dokka.base.DokkaBase": """{ "templatesDir": "${projectDir.toString().replace('\\', '/')}/dokka-templates" }"""])
+}
diff --git a/dokka-templates/README.md b/dokka-templates/README.md
new file mode 100644
index 0000000..0891177
--- /dev/null
+++ b/dokka-templates/README.md
@@ -0,0 +1,4 @@
+# Customize Dokka's HTML. 
+To customize Dokka's HTML output, place a file in this folder.
+Dokka will find a template file there. If the file is not found, a default one will be used.
+This folder is defined by the templatesDir property.
\ No newline at end of file
diff --git a/gradle/dokka.gradle.kts b/gradle/dokka.gradle.kts
index 2470ded..ba6956a 100644
--- a/gradle/dokka.gradle.kts
+++ b/gradle/dokka.gradle.kts
@@ -27,6 +27,8 @@
 
 tasks.withType(DokkaTaskPartial::class).configureEach {
     suppressInheritedMembers.set(true)
+    pluginsMapConfiguration.set(mapOf("org.jetbrains.dokka.base.DokkaBase" to """{ "templatesDir" : "${rootProject.projectDir.toString().replace('\\', '/')}/dokka-templates" }"""))
+
     dokkaSourceSets.configureEach {
         jdkVersion.set(11)
         includes.from("README.md")