Mentioned IntoIterator earlier in keyword 'for' docs

Author: Nicholas-Baron

src/libstd/keyword_docs.rs

@@ -473,8 +473,8 @@ mod fn_keyword {}
 /// * `for` is also used for [higher-ranked trait bounds] as in `for<'a> &'a T: PartialEq<i32>`.
 ///
 /// for-in-loops, or to be more precise, iterator loops, are a simple syntactic sugar over a common
-/// practice within Rust, which is to loop over an iterator until that iterator returns `None` (or
-/// `break` is called).
+/// practice within Rust, which is to loop over anything that implements `IntoIterator` until the
+/// temporary iterator returns `None` (or `break` is called).
 ///
 /// ```rust
 /// for i in 0..5 {