Improve sendVideoAttentionTime comment, making it clear what the argument represents

Author: SHession

thrift/native.thrift

@@ -186,13 +186,14 @@ service Gallery {
 service Videos {
     void insertVideos(1:list<VideoSlot> videoSlots),
     void updateVideos(1:list<VideoSlot> videoSlots),
-    /*
+    /**
     * This method is used to submit media tracking events for videos from the web layer.
-    * */
+    */
     void sendVideoEvent(1:VideoEvent videoEvent),
-    /*
+    /**
     * This method is used to submit component attention time tracking updates for videos from the web layer.
-    * */
+    * The argument is a map of videoIds to attention milliseconds, matching the native app tracking submission type.
+    */
     void sendVideoAttentionTime(1:map<string, i64> componentAttentionMs),
     /**
      * This method is used by the web layer to instruct the native layer to activate or deactivate fullscreen mode