Mention CDN minification as an alternative to compress_html (#1217)

* Mention CDN minification as an alternative to compress_html

* Add warning notice to caution statement

Author: ohadschn

docs/_docs/05-configuration.md

@@ -642,3 +642,7 @@ compress_html:
 ```
 
 **Caution:** Inline JavaScript comments can cause problems with `compress.html`, so be sure to `/* comment this way */` and avoid `// these sorts of comments`.
+{: .notice--warning}
+
+**Note:** CDN services such as CloudFlare provide optional automatic minification for HTML, CSS, and JavaScript. If you are serving your site via such a service and have minification enabled, this configuration might be redundant.
+{: .notice--info}