Update feature-flag in documentation
It appears that the feature flag has been changed from `std` to `alloc` some time in the past. However, the corresponding documentation attribute has been left unchanged.
@@ -53,7 +53,7 @@ pub mod buf_reader;
/// Stream wrapper which provides a `ResetStream` impl for `StreamOnce` impls which do not have
/// one.
#[cfg(feature = "alloc")]
-#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
+#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
pub mod buffered;
#[cfg(feature = "std")]
#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
