It has a better look and navigation.
The steps to contribute are much simpler now.
You can edit any page by clicking on the edit page button at the bottom of the page.
You can edit the text and change images right from your browser
The sidebar can also be edited by dragging and dropping the sidebar items.
Detailed steps: frappeframework.com/contribute
Contribute to the Frappe Wiki App here
Link to ERPNext Documentation Announcement: New Documentation Website / Wiki