A couple basic "facts of status" and rules about UDN:
Keep in mind this is a backup, not a live, updated website.
At this time, please do not report bad links, broken images or examples, or script snippets without formatting - all those things are already being taken care of, however slowly.
I will not be making major additions or changes to the documentation - there will be constant mentions of Mozilla and its products, WebExtensions, and all kinds of things that are entirely unrelated to UXP or the direction of its development. Some content may be reverted if it was altered to fit WebExtensions, or removed if it's a snippet about WebExtension changes that apply to the page's topic. Future changes will hopefully go much further, such as adding Pale Moon and Basilisk to the browser compatibility tables.
The Archive directory contains much of the more important information, particularly regarding XUL and Overlay Extensions. This directory will remain as-is in this backup for now. Maybe re-integration can be in the "future changes" list as well, but it's a big folder.
I will also be asking the development team questions about what should be retained and what can safely be removed from the backup as I go. If you are not a member of staff but have some direct input regarding the pages or sections in question, don't hesitate to speak up!