sphinx-togglebutton: Make solution admonitions collapsed by default

[rkdarst]

• Add this extensions as a hard dependency and sets up the solution to start collapsed by default.
• https://github.com/executablebooks/sphinx-togglebutton
• Review: general check unless someone wants to takelocally and compile it. A test is in the docs: directives.rst

[annefou]

I did not manage to make it work on my windows laptop. But it is probably not super important at this stage. Shall we merge it?

[rkdarst]

On Sun, Sep 13, 2020 at 05:09:44AM -0700, Anne Fouilloux wrote:

I did not manage to make it work on my windows laptop. But it is probably not super important at this stage. Shall we merge it?

Interesting... I see it works here:: https://coderefinery.github.io/sphinx-lesson/branch/rkdarst--togglebutton/directives/

I'd propose we merge and continue debugging... then we can see if it works live and get those previews