Refine raw Window scrolling documentation example.

Avoid skipping last batch, avoid out-of-bounds exception.

Closes #3352
Co-authored-by: r6hk <rennen0929@gmail.com>

src/main/antora/modules/ROOT/pages/repositories/scrolling.adoc

@@ -7,7 +7,7 @@ You can define simple sorting expressions by using property names and define sta
 You can concatenate expressions to collect multiple criteria into one expression.
 
 Scroll queries return a `Window<T>` that allows obtaining the element's scroll position to fetch the next `Window<T>` until your application has consumed the entire query result.
-Similar to consuming a Java `Iterator<List<…>>` by obtaining the next batch of results, query result scrolling lets you access the a `ScrollPosition`  through `Window.positionAt(...)`.
+Similar to consuming a Java `Iterator<List<…>>` by obtaining the next batch of results, query result scrolling lets you access the a `ScrollPosition` through `Window.positionAt(…)`, as in the following example:
 
 [source,java]
 ----
@@ -18,9 +18,13 @@ do {
     // consume the user
   }
 
+  if (users.isLast() || users.isEmpty()) {
+    break;
+  }
+
   // obtain the next Scroll
   users = repository.findFirst10ByLastnameOrderByFirstname("Doe", users.positionAt(users.size() - 1));
-} while (!users.isEmpty() && users.hasNext());
+} while (!users.isEmpty());
 ----
 
 [NOTE]
@@ -38,6 +42,8 @@ In a similar way, providing a `Limit` object allows you to define a dynamic limi
 Read more on dynamic sorting and limiting in the xref:repositories/query-methods-details.adoc#repositories.special-parameters[Query Methods Details].
 ====
 
+Scrolling through consuming `Window` instances requires quite a few conditionals to reach optimum database round-trips and can quickly become a repetitive task that can be simplified using `WindowIterator`.
+
 `WindowIterator` provides a utility to simplify scrolling across ``Window``s by removing the need to check for the presence of a next `Window` and applying the `ScrollPosition`.
 
 [source,java]