doc: add doc for dynamic comment loading

docs/docs/extras/advanced-integration.rst

@@ -23,3 +23,34 @@ Now, either include `count.min.js` if you want to show only the comment count
 
 You can have as many comments counters as you want in a page, and they will be
 merged into a single `GET` request.
+
+Asynchronous comments loading
+-----------------------------
+
+Isso will automatically fetch comments after `DOMContentLoaded` event. However
+in the case where your website is creating content dynamically (eg. via ajax),
+you need to re-fetch comment thread manually. Here is how you can re-fetch the
+comment thread:
+
+.. code-block:: js
+
+    window.Isso.fetchComments()
+
+It will delete all comments under the thread but not the PostBox, fetch
+comments with `data-isso-id` attribute of element `section#isso-thread` (if that
+attribute not exists, fallback to `window.location.pathname`), then fill
+comments into the thread. In other words, you should change `data-isso-id`
+attribute of element `section#isso-thread` (or modify the pathname with
+`location.pushState`) before you can get new comments. And the thread element
+itself should *NOT* be touched or removed.
+
+If you removed the `section#isso-thread` element, just create another element
+with same TagName and ID in which you wish comments to be placed, then call the
+`init` method of `Isso`:
+
+.. code-block:: js
+
+    window.Isso.init()
+
+Then Isso will initialize the comment section and fetch comments, as if the page
+was loaded.