Make Patternslib JavaScript bundle configurable.

Author: thet

_config.yml

@@ -1,6 +1,7 @@
 title: Patterns
 author: Cornelis G. A. Kolbach
 summary: Patternslib is a free toolkit that aims to bring web design and development closer together.
+bundle_url: https://cdn.jsdelivr.net/npm/@patternslib/[email protected]/dist/bundle.min.js
 patternslib_version: 9.8.0
 baseurl: /
 domain: www.patternslib.com