revert stabilization of core::task::ready!

(cherry picked from commit 5f7e7d2)

Author: ibraheemdev

library/core/src/task/mod.rs

@@ -11,5 +11,5 @@ mod wake;
 pub use self::wake::{Context, RawWaker, RawWakerVTable, Waker};
 
 mod ready;
-#[stable(feature = "ready_macro", since = "1.56.0")]
+#[unstable(feature = "ready_macro", issue = "70922")]
 pub use ready::ready;

library/core/src/task/ready.rs

@@ -8,6 +8,8 @@
 /// # Examples
 ///
 /// ```
+/// #![feature(ready_macro)]
+///
 /// use std::task::{ready, Context, Poll};
 /// use std::future::{self, Future};
 /// use std::pin::Pin;
@@ -27,6 +29,7 @@
 /// The `ready!` call expands to:
 ///
 /// ```
+/// # #![feature(ready_macro)]
 /// # use std::task::{Context, Poll};
 /// # use std::future::{self, Future};
 /// # use std::pin::Pin;
@@ -45,7 +48,7 @@
 ///     # Poll::Ready(())
 /// # }
 /// ```
-#[stable(feature = "ready_macro", since = "1.56.0")]
+#[unstable(feature = "ready_macro", issue = "70922")]
 #[rustc_macro_transparency = "semitransparent"]
 pub macro ready($e:expr) {
     match $e {