Translation of matplotlib core project website.

Hi Matplotlib team,

With support from the CZI [Scientific Python Community and Communications Infrastructure](https://scientific-python.org/doc/scientific-python-community-and-communications-infrastructure-2022.pdf) grant, [Quansight Labs](https://labs.quansight.org/) is able to offer assistance with developing and publishing translations of the brochure websites for the [Scientific Python Core Project](https://scientific-python.org/specs/core-projects/). You may have seen that translations into some languages are already available for https://numpy.org/, with a version switcher in the top right corner; we're offering to help core projects integrate something similar into their websites. Our aim is to accomplish this in a way that requires minimal effort from the core project maintainers.

I've been tasked with setting up the software infrastructure for translations, and am posting issues today to ask core project teams if they would like to participate. I've published an FAQ here: https://scientific-python-translations.github.io/faq/, with more information. Please take a look and let me know if you have any questions. If you decide to participate, I can begin setting up the translation infrastructure, which will require no work or input from maintainer teams (See [here](https://scientific-python-translations.github.io/faq/#what-work-is-expected-from-project-maintainers) in the FAQ for more details on the process).

I had briefly discussed this translation project with the team on gitter last year. At that point there was some uncertainty because I did not know how to set up the translation infrastructure for Matplotlib's website, but in the since then I've become more experienced with Crowdin, the translation management platform we are using. Setting things up shouldn't be an issue any longer.

Start with the linked translation FAQ, especially the section describing expected work from project maintainers, and review the existing mpl-brochure-site website. The issue is a participation request rather than a defined code task; completion depends on deciding whether to participate and coordinating translation infrastructure with the proposer.

Written by the indexing model from the issue text.