I just went to the ADN site and noticed a complete redesign. It appears that Salesforce will be introducing the Apex Wiki. This looks to be the new home for all the toolkits and documentation on developing with Salesforce (native, composite, api, ajax, apex).
While writing this post, the ADN site design was flip-flopping between old and new. I imagine they will let us know exactly what the site is to be used for, who can edit, etc. etc. It appears that it will be open for anyone with a developer account to edit the pages. I was able to login with my developer account ID and get to an edit page.
The direct link to the wiki is https://wiki.apexdevnet.com.