Auto-scrape Examples in Docs

# What
It's hard to put in words, but have a look at this example from `bevy`: https://docs.rs/bevy/0.16.1/bevy/prelude/struct.Events.html#method.send


Also see [this explanation](https://docs.rs/bevy/0.16.1/scrape-examples-help.html).

# Why
I think the "manual style" of adding some code to the doc string is very good, e.g.:

```rust
/// Get value for given key.\
///
/// # Example
/// ```
/// ...
/// ```
pub fn get(&self, k: &str) -> Option<...> {
...
```

However sometimes it helps to see certain methods used in a wider context or more complex examples. While one can manually link examples, I think the rendering of `rustdoc` is great and avoiding manual maintenance burden is always a plus.

I think this greatly helps people to understand what certain methods do.

# How
IIRC [docs.rs](https://docs.rs/) uses a nightly compiler. So all we would need to do is to [follow `bevy`](https://github.com/bevyengine/bevy/blob/1a410efd246e0f2f41766d47e300f474c8379b2e/Cargo.toml#L4357).

Start with the linked Bevy example, the docs.rs scrape-examples-help explanation, and the referenced Cargo.toml dependency. Investigate how rustdoc and docs.rs could support automatically scraped examples without manual links. Done means the approach is implemented and documented well enough for wider-context examples to render reliably.

Written by the indexing model from the issue text.