doc(alias) pending() to never (#2613)

It can be legitimately to look for the future that _never_ resolves using the name `never`. This PR ensures `pending()` shows up when making such queries.

futures-util/src/future/pending.rs

@@ -33,6 +33,7 @@ impl<T> FusedFuture for Pending<T> {
 /// unreachable!();
 /// # });
 /// ```
+#[cfg_attr(docsrs, doc(alias = "never"))]
 pub fn pending<T>() -> Pending<T> {
     assert_future::<T, _>(Pending { _data: marker::PhantomData })
 }