[Docs][MaterialSplitButton.java] Updated usage documentation

Resolves #4795

  - bf180a9 by Leo <[email protected]>

PiperOrigin-RevId: 766667719

Author: LeoAndo

lib/java/com/google/android/material/button/MaterialSplitButton.java

@@ -51,7 +51,7 @@
  *         app:icon="@drawable/ic_edit_vd_theme_24dp"
  *         app:iconGravity="start"/>
  *     <Button
- *        style="?attr/materialIconSplitButtonFilledStyle"
+ *        style="?attr/materialSplitButtonIconFilledStyle"
  *        android:layout_width="wrap_content"
  *        android:layout_height="wrap_content"
  *        android:contentDescription="@string/split_button_label_chevron"