Rollup merge of #128619 - glandium:last_chunk, r=scottmcm

Correct the const stabilization of `<[T]>::last_chunk`

`<[T]>::first_chunk` became const stable in 1.77, but `<[T]>::last_chunk` was left out. This was fixed in 3488679, which reached stable in 1.80, making `<[T]>::last_chunk` const stable as of that version, but it is documented as being const stable as 1.77. While this is what should have happened, the documentation should reflect what actually did happen.

library/core/src/slice/mod.rs

@@ -522,7 +522,7 @@ impl<T> [T] {
     /// ```
     #[inline]
     #[stable(feature = "slice_first_last_chunk", since = "1.77.0")]
-    #[rustc_const_stable(feature = "slice_first_last_chunk", since = "1.77.0")]
+    #[rustc_const_stable(feature = "const_slice_last_chunk", since = "1.80.0")]
     pub const fn last_chunk<const N: usize>(&self) -> Option<&[T; N]> {
         if self.len() < N {
             None