* Add `middleware::from_fn` for creating middleware from async fns
* More trait impls for `Next`
* Make `Next::run` consume `self`
* Use `.router_layer` in example, since middleware returns early
* Actually `Next` probably shouldn't impl `Clone` and `Service`
Has implications for backpressure and stuff
* Simplify `print-request-response` example
* Address review feedback
* add changelog link
* extra: Add `Cached` extractor
`Cached` wraps another extractor and caches its result in request
extensions.
* Use newtype to avoid overriding extensions of the same type
* Rename type param
* Add `axum-extra` crate
Empty for now but now we have a place to put stuff.
I'll make a PR for moving over https://github.com/davidpdrsn/axum-resource.
* remove `authors` field from `Cargo.toml`s
