fixed a typo in traits.md

line 46: Trait functions are **are** not allowed to be [`async`] or [`const`].
now: Trait functions are not allowed to be [`async`] or [`const`].

src/items/traits.md

@@ -43,7 +43,7 @@ trait Example {
 }
 ```
 
-Trait functions are are not allowed to be [`async`] or [`const`].
+Trait functions are not allowed to be [`async`] or [`const`].
 
 ## Trait bounds