adjust filename to indicate that customize JS is minified

docs/_includes/footer.html

@@ -9,7 +9,7 @@
 
 {% if page.slug == "customize" %}
 <script src="{{ site.baseurl }}assets/js/raw-files.js"></script>
-<script src="{{ site.baseurl }}assets/js/customize.js"></script>
+<script src="{{ site.baseurl }}assets/js/customize.min.js"></script>
 {% endif %}
 
 {% comment %}