Update Customizer.html

apps/ac_ac/Customizer.html

@@ -777,7 +777,13 @@ console.log(AppSource)
   <p id="MessageView" style="display:none; color:red"></p>
 
   <button id="UploadButton">Upload</button>
-</p><p> &nbsp; </p>
+</p><p>
+  This application is based on the author's
+  [Analog Clock Construction Kit (ACCK)](https://github.com/rozek/banglejs-2-analog-clock-construction-kit).
+  If you need a different "clockwork", clock size calculation or clock face,
+  or specific clock hands or complications, just follow the link to learn how to
+  implement your own clock parts.
+</p>
  </body>
 </html>