message: Derive `Default` for `Rainbow` in `geometry` example
diff: @@ -20,12 +20,11 @@ mod rainbow {
  Element, Layout, Length, Point, Rectangle, Size, Vector,
  };
  + #[derive(Debug, Clone, Copy, Default)]
  pub struct Rainbow;
  - impl Rainbow {
  - pub fn new() -> Self {
  - Self
  - }
  + pub fn rainbow() -> Rainbow {
  + Rainbow
  }
  impl<Message, B, T> Widget<Message, Renderer<B, T>> for Rainbow
  @@ -164,7 +163,7 @@ mod rainbow {
  use iced::widget::{column, container, scrollable};
  use iced::{Element, Length, Sandbox, Settings};
  -use rainbow::Rainbow;
  +use rainbow::rainbow;
  pub fn main() -> iced::Result {
  Example::run(Settings::default())
  @@ -187,7 +186,7 @@ impl Sandbox for Example {
  fn view(&self) -> Element<()> {
  let content = column![
  - Rainbow::new(),
  + rainbow(),
  "In this example we draw a custom widget Rainbow, using \
  the Mesh2D primitive. This primitive supplies a list of \
  triangles, expressed as vertices and indices.",
  