Add docs

Author: CrisBarreiro

js-messaging/js-messaging-api/src/main/java/com/duckduckgo/js/messaging/api/AdsjsMessaging.kt

@@ -18,8 +18,8 @@ package com.duckduckgo.js.messaging.api
 
 import org.json.JSONObject
 
-abstract class WebViewCompatMessageCallback {
-    abstract fun process(
+interface WebViewCompatMessageCallback {
+    fun process(
         featureName: String,
         method: String,
         id: String?,
@@ -37,6 +37,7 @@ interface WebCompatMessageHandler {
      *
      * @param jsMessage The JavaScript message to be processed.
      * @param jsMessageCallback An optional callback to handle the result of the message processing.
+     * @param onResponse A callback function to send a response back to the JavaScript code.
      */
 
     //TODO: Simplify by removing the onResponse and callback