Closes https://github.com/zed-industries/zed/issues/17911
This PR enables dark mode on the documentation. This is done without any
special plugins, just pure JavaScript and CSS variables. I may open
fast-follow PRs to fine-tune design and code details that haven't been
super polished yet. For example, when switching to dark mode, the
`class` attribute on the `html` tag would change immediately, whereas
other attributes such as `data-theme` and `data-color-scheme` would
require a full refresh. This seems to be resolved, but not 100%
confident yet.
---
Release Notes:
- Enabled dark mode on the documentation
To ease navigating on pages that are long and having a birds-eye view of
all the available content.
This is done client-side and done via the files initially generated by
the `mdbook-pagetoc` plugin ([crates.io link
here](https://crates.io/crates/mdbook-pagetoc)).
<img width="600" alt="Screenshot 2024-07-25 at 13 34 08"
src="https://github.com/user-attachments/assets/a78c69e5-8cc4-4414-9d9c-27a4ceb27620">
---
Release Notes:
- N/A
---------
Co-authored-by: Marshall Bowers <elliott.codes@gmail.com>
