Add a note about changed filenames to the change log

index.html

@@ -4470,6 +4470,12 @@ ActiveRecord::Base.include_root_in_json = false
       <li>
         Several improvements to the online documentation.
       </li>
+      <li>
+        Due to upgraded development tools, the annotated sources of the example
+        code as well as the sourcemap of the minified bundle have changed
+        filenames. Aliases and redirects in the old locations are kept for
+        backwards compatibility.
+      </li>
     </ul>
 
     <b class="header" id="1.4.0">1.4.0</b> &mdash; <small><i>Feb. 19, 2019</i></small>