Create new Read the docs theme with custom index

[jessica-mitchell]

This PR introduces a new theme (based on Sphinx Material) for the Read the docs documentation.
It also include a new template for index.html. Thanks to @jougs for developing a more interactive and attractive theme!

The goal is to provide users with different ways to explore the docs, improve the context for the different guides and resources, and enhance the overall theme.

Set as draft as discussion and bit more tweaking is needed. Also #2283 needs to be merged first.

[steffengraber]

Great, a big step for the documentation.
To improve the mobile view, I have just one small note in custom.css.
A general question: is it necessary to have the full bootstrap stack (js and css) in the code? Or is it not possible to leave some of it out?
One more note: There are also many content adjustments that don't necessarily have anything to do with theme customization. Wouldn't it have been better to put this in another pull request?

[jessica-mitchell]

@steffengraber
I adjusted the padding for smaller screens, thanks

A general question: is it necessary to have the full bootstrap stack (js and css) in the code?

I just followed steps from the bootstrap site, and it might be excessive to have it all, perhaps in follow up PR I can look at simplifying this

There are also many content adjustments that don't necessarily have anything to do with theme customization. Wouldn't it have been better to put this in another pull request?

Yah probably, but now it would be very time consuming to review commits, it largely stemmed from trying to get the output to look decent and I probably got carried away with other fixes along the way.

[jessica-mitchell]

@heplesser I fixed up the API, including the spacing between elements in the kernel attributes which was mentioned at the NEST conference https://nest-test.readthedocs.io/en/rtd-theme/ref_material/pynest_apis.html

[pnbabu]

@jessica-mitchell can we have a link for NESTML on the main menu? Instead of models, we can have something like built-in models and custom models and the latter could point to the NESTML page.

[jessica-mitchell]

Instead of models, we can have something like built-in models and custom models and the latter could point to the NESTML page.

@pnbabu
I was thinking about create models for NESTML, or maybe customize models?

[jougs]

I just had another walk though and here's some things I noticed. I also noticed that some of the things we discussed earlier are fixed now and I like those much better now :-)

• I agree with @pnbabu and think that "Built-in models" and "Custom models" represent reality much better than just "Models" and "Customize models"
• When I'm at the index of the developer space, the "Related Projects" button at the top takes me to the maze, as does "Contact us"

[pnbabu]

Instead of models, we can have something like built-in models and custom models and the latter could point to the NESTML page.

@pnbabu I was thinking about create models for NESTML, or maybe customize models?

I see that the Customize models link is on the Models page. It is better to have it linked from the main page instead as Built-in and Custom models.

[gtrensch]

Thank you for this extensive contribution! It looks very good to me. 👍

[terhorstd]

This has become a very long PR with more and more changes accumulating. @jougs might have some minor points left, but @gtrensch has re-reviewed and accepted, so I'd merge this now. All lights are green.

If there are remaining points, don't hesitate to open new issues (with smaller scope).