Don't use associated type bounds in docs until it is stable

Author: iluuu1994

src/libcore/iter/traits/collect.rs

@@ -194,11 +194,10 @@ pub trait FromIterator<A>: Sized {
 /// `Item`:
 ///
 /// ```rust
-/// #![feature(associated_type_bounds)]
-///
 /// fn collect_as_strings<T>(collection: T) -> Vec<String>
 /// where
-///     T: IntoIterator<Item: std::fmt::Debug>,
+///     T: IntoIterator,
+///     T::Item: std::fmt::Debug,
 /// {
 ///     collection
 ///         .into_iter()