Change RTN to use .. again

compiler/rustc_hir/src/hir.rs

@@ -2413,7 +2413,7 @@ pub enum ImplItemKind<'hir> {
 /// * the `A: Bound` in `Trait<A: Bound>`
 /// * the `RetTy` in `Trait(ArgTy, ArgTy) -> RetTy`
 /// * the `C = { Ct }` in `Trait<C = { Ct }>` (feature `associated_const_equality`)
-/// * the `f(): Bound` in `Trait<f(): Bound>` (feature `return_type_notation`)
+/// * the `f(..): Bound` in `Trait<f(..): Bound>` (feature `return_type_notation`)
 #[derive(Debug, Clone, Copy, HashStable_Generic)]
 pub struct AssocItemConstraint<'hir> {
     pub hir_id: HirId,