message: Fix `iced_native` mention of old `window::Backend`
diff: //! - Event handling for all the built-in widgets
  //! - A renderer-agnostic API
  //!
  -//! To achieve this, it introduces a bunch of reusable interfaces:
  +//! To achieve this, it introduces a couple of reusable interfaces:
  //!
  //! - A [`Widget`] trait, which is used to implement new widgets: from layout
  //! requirements to event and drawing logic.
  //! - A bunch of `Renderer` traits, meant to keep the crate renderer-agnostic.
  -//! - A [`window::Backend`] trait, leveraging [`raw-window-handle`], which can be
  -//! implemented by graphical renderers that target _windows_. Window-based
  -//! shells (like [`iced_winit`]) can use this trait to stay renderer-agnostic.
  //!
  //! # Usage
  //! The strategy to use this crate depends on your particular use case. If you
  //! [`druid`]: https://github.com/xi-editor/druid
  //! [`raw-window-handle`]: https://github.com/rust-windowing/raw-window-handle
  //! [`Widget`]: widget/trait.Widget.html
  -//! [`window::Backend`]: window/trait.Backend.html
  //! [`UserInterface`]: struct.UserInterface.html
  //! [renderer]: renderer/index.html
  #![deny(missing_docs)]
  