add makdown (`---`) separator for slides separator

[guillaumeLamanda]

The current separator between two slides is 3 lines break.
Markdown has a separator (---) build in.

I think it would make sense to parse this separator for slides.
What do you think?

[hgwood]

Why not, though compatibility with content using 3 lines must not be broken. Relevant code is here.

[jermarchand]

Why not just use chapters as slide separators?
and for specific cases use the --- as proposed by Guillaume

[hgwood]

I'm not sure I understand what you mean.

[jermarchand]

Example :

In the file : https://raw.githubusercontent.com/Zenika-Training/formation-kubernetes-user/master/Slides/00_agenda.md?token=GHSAT0AAAAAABRIZC4ZY2Q6N7MOGG4YMDH4YSMHN7A

Each "#"/"##"/"###"/"####" indicate a new slide/chapter, no ?

So instead of having 3 empty lines to indicate to the renderer to create a new slide
Each new slide/chapter can be a new slide.

[zigarn]

Some trainings use multiple title levels in same slide on purpose, so titles (at least more than 3 ###) are not an indicator of slide change.