Drop reverted stabilizations from release notes

RELEASES.md

@@ -6,7 +6,6 @@ Language
 
 - [The 2021 Edition is now stable.][rust#88100]
   See [the edition guide][rust-2021-edition-guide] for more details.
-- [You can now specify explicit discriminant values on any Rust enum.][rust#86860]
 - [The pattern in `binding @ pattern` can now also introduce new bindings.][rust#85305]
 - [Union field access is permitted in `const fn`.][rust#85769]
 
@@ -51,8 +50,6 @@ Stabilised APIs
 ---------------
 
 - [`std::os::unix::fs::chroot`]
-- [`Iterator::intersperse`]
-- [`Iterator::intersperse_with`]
 - [`UnsafeCell::raw_get`]
 - [`BufWriter::into_parts`]
 - [`core::panic::{UnwindSafe, RefUnwindSafe, AssertUnwindSafe}`]