docs: Allow to have dropdown menu to show the API of reporters

[glemaitre]

closes #1095

It is a wip PR to show that we can get a sort of dropdown menu with several level to show the API documentation of reporters, without the feeling that there is so much information at the top level.

The trick is to have a directory structure:

reference/
├── index.rst
├── report.rst
└── report/
    └── estimator_report.rst

that creates the tree on the navigation sidebar. The not ideal thing is the content of report.rst. We need to think what content we want in this intermediate page. However, I think it is a good start to explore.

A couple of screen:

(I obviously broke the API auto-generated documentation but it should be possible to fix it).

[github-actions]

Documentation preview @ c18e983

[glemaitre]

I let the PR in this stage for the moment. If anyone wants to take over, please do not hesitate.

[auguste-probabl]

@sylvaincom What do you think?

[sylvaincom]

I like what I see, thanks

[sylvaincom]

@auguste-probabl did you want to take this over? Or should I?

[auguste-probabl]

@auguste-probabl did you want to take this over? Or should I?

I can take it DW

[auguste-probabl]

@sylvaincom @MarieS-WiMLDS I've been expanding on this PR, and I found something which I need your opinion on: the API index page (https://skoredoc.k.probabl.dev/1302/reference/index.html) no longer lists all the public class/functions using the autosummary table, like we have currently (https://skore.probabl.ai/0.6/api.html). Instead we have a table of contents to navigate to the individual pages.

As far as I can tell, we can't have both a summary table with everything, and drop-downs in the sidebar. Which do you prefer?

@glemaitre Feel free to correct me if there's a way to do it

[MarieSacksick]

To make sure, are you talking about this page?

If we have to choose, I prefer to have the dropdown and not the autosummary than having a looooong list on the left with the autosummary.

[auguste-probabl]

To make sure, are you talking about this page?

Yes exactly

[glemaitre]

We might be able to increase the depth of the toc tree but indeed it will not be as nice as what we had before.

I think that I would be fine with a slightly deeper toc tree since that if you click on it, you will end up in a subsection. Perfectly, in the future, I would be happy that we have a manual generation of all public methods as in scikit-learn: https://scikit-learn.org/stable/api/index.html

However, I'm also OK if someone has stronger opinion on this one.

[sylvaincom]

If we have to choose, I prefer to have the dropdown and not the autosummary than having a looooong list on the left with the autosummary.

+1