Find your way around docs

Long pages and deep folder trees are easier to navigate:

• Table of contents. A new Outline button on every doc page opens a table of contents built from its headings. Click an entry to jump to that section.
• The sidebar remembers. Folders you open stay open as you move between pages and after a reload, and opening a page from a link expands the folders it lives in.
• Expand all and collapse all buttons in the sidebar header open or close every folder at once.

Also new: notifications can now be marked as read or unread individually, from the notifications page or the header tray.