The main motivation of these changes is having a short linkable example of how to escape URLs in various command-line shells, because this question comes up often and gets incorrectly (and annoyingly) reported as a bug.

Since there'd be a lot of repetition when showing examples for different shells, I decided to add the sphinx-design extension, to be able to have support for tabs (and other things that might be useful in the future). It's recommended by the furo-theme author and it's maintained by the developer of the myst-parser extension which Streamlink already uses for markdown support in the docs.
https://sphinx-design.readthedocs.io/en/furo-theme/index.html

This PR also rewrites and clarifies some sections and fixes broken links. I also replaced the tutorial's example URL with something more neutral, because the previous URL was set by chrippa, who apparently was a starcraft fan in the early days of Twitch, hence the day9tv example.

The examples are not super strict, because on BASH for example, the nullglob option could be set, but that's mostly irrelevant for interactive use. I tried to cover the most common pitfalls though when pasting URLs.

Please see the docs preview.

Both sphinx-design and myst-parser extensions are currently holding back the upgrade to Sphinx 6 if the furo-theme would get bumped to the latest version. A new release of the extensions should be coming up shortly though (highly requested by lots of people). I will have a look at bumping furo and thus Sphinx to 6.0.0 which will drop support for py37 and which will finally drop unneeded bloat like jquery and underscore. 🤮

The py37 drop also made me have a look at the netlify docs-preview build config, but that one is unfortunately still stuck on py38, and they've even made their build-image repo closed source for development pace reasons, with eventual Python upgrades promised on their forums 😞.