Auto merge of rust-lang#8706 - lupd:cast-abs-to-unsigned, r=xFrednet

Fix formatting of `cast_abs_to_unsigned` docs

The "use instead" section of the example was not being formatted as Rust code, and the "configuration" documentation was being formatted as Rust code.

changelog: `[cast_abs_to_unsigned]` Fix example/configuration formatting

Author: bors

clippy_lints/src/casts/mod.rs

@@ -487,6 +487,7 @@ declare_clippy_lint! {
     /// let y: u32 = x.abs() as u32;
     /// ```
     /// Use instead:
+    /// ```rust
     /// let x: i32 = -42;
     /// let y: u32 = x.unsigned_abs();
     /// ```