Allow links in Notebook to timestamps

There should be a way to click on a link inside the notebook and jump to the corresponding part of the video.

Ideas:

<a href="" data-chapter="chapter1">Click here for chapter 1</a>

Con: weird HTML Pro: it allows us to jump to the timestamp, without jumping in the HTML.

<a href="#chapter1">Click here for chapter 1</a> Click [here](#chapter1)

Pro: standard HTML or markdown Con: it jumps to the anchor "#chapter1" no matter if we want that or not.

<a href="#timestamp-chapter1">Click here for chapter 1</a> Click [here](#timestamp-chapter1)

Pro: allows us to jump to the timestamp, without jumping in the HTML. (The anchor "#timestamp-chapter1" doesn't exist.) Con: a bit verbose.