Fix typo

Author: RuairidhWilliamson

clippy_lints/src/anon_trait_import.rs

@@ -13,7 +13,7 @@ declare_clippy_lint! {
     /// Checks for `use Trait` where the Trait is not used directly.
     ///
     /// ### Why is this bad?
-    /// Traits imported that aren't used directly can be imported anonymously `use Trait as _`. It is more explicit and can be usedful to show which imports are required for traits.
+    /// Traits imported that aren't used directly can be imported anonymously `use Trait as _`. It is more explicit and can be useful to show which imports are required for traits.
     ///
     /// ### Example
     /// ```no_run