Update the release announcement for version 2.1

ANNOUNCE

@@ -1,14 +1,48 @@
 GNUstep Objective-C Runtime 2.1
-===============================
+=================================
 
-This the first update to the second major release of the GNUstep Objective-C
+This is first update to the second major release of the GNUstep Objective-C
 runtime (a.k.a.  libobjc2).  This runtime was designed to support the features
 of modern dialects of Objective-C for use with GNUstep and other Objective-C
 programs.
 
 Highlights of this release include:
 
-- ?
+- Numerous improvements to the Objective-C++ exception interoperation code.
+  The runtime now dynamically detects whether the libcxxrt or libsupc++ variant
+  of the Itanium C++ Exception ABI is being used
+
+- Sending a message to `super` where the corresponding method did not exist was
+  silently ignored in previous versions of the runtime.  This now correctly
+  invokes the forwarding hooks and so (with an implementation of the Foundation
+  framework, such as GNUstep Base or WinObjC) will trigger an exception or
+  invoke `forwardInvocation:`.
+
+- The checks for overloaded memory management methods were incorrect, causing
+  some classes to be incorrectly opted into ARC fast paths.  These checks are
+  now correct.
+
+- Several memory management bugs in corner cases of weak reference management
+  were fixed.
+
+- The ARM assembly implementation of `objc_msgSend` now correctly restores the
+  stack after calling a forwarding implementation.  This bug caused stack
+  corruption and usually crashing on ARM.
+
+- The ARC code has been rewritten as C++, using a well-tested third-party
+  Robin-Hood hash table to store weak references, replacing the home-grown
+  version.  This improves performance and reduces the likelihood of bugs
+  arising from the hash table implementation.
+
+- Control Flow Guard (CGF) checks were added on Windows on x86 (32- and
+  64-bit).  If Objective-C code is compiled with CFG enabled then
+  `objc_msgSend` will crash if it attempts to jump to an address that is not a
+  valid function entry point.
+
+- The function signatures in the blocks headers were updated for compatibility
+  with recent macOS releases.
+
+- Support for the C11 _Atomic type qualifier in property metadata was added.
 
 You may obtain the code for this release from git and use the 2.1 branch: