Update src/stream/into_stream.rs

Co-Authored-By: Stjepan Glavina <[email protected]>

Author: yoshuawuyts

src/stream/into_stream.rs

@@ -14,7 +14,7 @@ use futures_core::stream::Stream;
 ///
 /// [`FromStream`]: trait.FromStream.html
 #[cfg_attr(feature = "docs", doc(cfg(unstable)))]
-#[cfg(feature = "unstable")]
+#[cfg(any(feature = "unstable", feature = "docs"))]
 pub trait IntoStream {
     /// The type of the elements being iterated over.
     type Item;