Write missing docs and reenable deny statements

wgpu/src/settings.rs

@@ -1,4 +1,10 @@
+/// The settings of a [`Renderer`].
+///
+/// [`Renderer`]: struct.Renderer.html
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
 pub struct Settings {
+    /// The bytes of the font that will be used by default.
+    ///
+    /// If `None` is provided, a default system font will be chosen.
     pub default_font: Option<&'static [u8]>,
 }