Feature: Headings hierarchy should also be visible in a already published document

[SalvaZaraes]

Problem

It is awesome that while you are formatting a document, the heading hierarchy it is visible -it helps you a lot-.
But, when that document is finally published, the heading hierarchy that appears in the left column, disappears.
Making it visible would help the reader to jump from heading to heading easily and to have brief resume of the different parts of the document.
I will add some screenshots for reference.

Solution

Adding the same headings hierarchy of the edit mode to the reader mode.

Edit Mode

Reader Mode