Book navigation block? Where is the book navigation block in Drupal 8?

The structure guide for Drupal 7 says you just need to turn the navigation menu on by enabling the block.


  ...One navigational aid you can use is the book navigation block,
  which you can enable on the blocks page administer >> site building >>
  blocks (Drupal 5 and 6) or Dashboard >> Structure >> Blocks (Drupal
  7). Enabling this block will turn on a menu that shows where the user
  is in your book; the menu is only visible when viewing the book.


But there doesn't appear to be a "book navigation block" in Drupal 8 as far as I can see.

Where is this block hiding in Drupal 8?
You need to click on one of the "Place Block" buttons displayed beside all the region names, a popup with all the unused blocks appears and you select it from the list to add it.