Normalize spelling

Author: garydgregory

src/main/java/org/apache/commons/collections4/list/TreeList.java

@@ -33,7 +33,7 @@
  * A {@code List} implementation that is optimized for fast insertions and
  * removals at any index in the list.
  * <p>
- * This list implementation utilises a tree structure internally to ensure that
+ * This list implementation utilizes a tree structure internally to ensure that
  * all insertions and removals are O(log n). This provides much faster performance
  * than both an {@code ArrayList} and a {@code LinkedList} where elements
  * are inserted and removed repeatedly from anywhere in the list.