Let's not mention the keyboard shortcut here, because that implies that it's different from the toolbar or menu methods of saving, which it's not.

The description of a checkpoint could also use some work: the important feature of a checkpoint is that you can go back to it if autosave saves a change you didn't want.

Finally, the first paragraph under the subheading 'closing notebooks' has absolutely no mention of closing notebooks. Let's merge the paragraph below into this to make the connection clearer.