Doc toc restructure proposal (minor)

[deargle]

@sauln I'd like to move some toc entries around on the docs, what do you think? Here's a potato screenshot of the current:

And here is sklearn's:

Following scikit-learn docs approach, I'd like to do the following with Kepler mapper docs:

• promote each entry under "User Guide" to level 1
• make a new level 1 page called "tutorials" that would list the tutorials pages
• make a new level 1 page called "case studies" that would list each of the currently called "advanced case studies"

So our new list on the left would be all level 1 headers (all links), and would be:

• background
• Getting started
• Tutorials
• examples
• applications
• case studies
• API

Sklearn docs have a dedicated "user guide" section that seems to have one page for each code class -- basically a similar structure as the API docs, but more exposition than would make sense in the api docstring. But we don't have enough content for that (yet).

Sklearn "tutorial" is a verbose opinionated ordered index to their "tutorials." They seem to use the index itself to make sure they have all use-case sequential steps covered. We currently just have an unordered collection of tutorials. We could at least make a guided index page.

Btw I am making a new "tutorial" on using the html vis. I plan to have a lot of gifs in it.

[deargle]

An extension on the above idea, using Flask's approach:

With flask, the TOC on the left is just level 1 entries on the page. The page includes the tocs from each of those pages with depth of 2. They call the whole collection the "User Guide," as we currently have. The benefit of this approach is that the headings are `ctrl+f``-able all from the index page, while it still keeps the left toc tidy.

[deargle]

Here's what I have so far. I like this.

[I removed this]

Edit: non-index pages still have the full TOC. I disabled fulltoc because I spent hours figuring out why the toc wasn't behaving like I expected, and it was because of that extension, so I hate it now.

[I removed this]

Edit -- back to captioned TOCs, like below:

[deargle]

@sauln here's a PR readthedocs build of what the change looks like https://kepler-mapper--239.org.readthedocs.build/en/239/

[deargle]

lol after the weekend, I like the fulltoc extension again. So the only thing this PR does is shoves the tutorials and case studies under the User's Guide TOC, instead of them being their own. I'm going to merge it since it's such a small docs change now.