Add Release Notes

Author: aheejin

llvm/docs/ReleaseNotes.md

@@ -239,18 +239,26 @@ Changes to the RISC-V Backend
 Changes to the WebAssembly Backend
 ----------------------------------
 
-The default target CPU, "generic", now enables the `-mnontrapping-fptoint`
+* The default target CPU, "generic", now enables the `-mnontrapping-fptoint`
 and `-mbulk-memory` flags, which correspond to the [Bulk Memory Operations]
 and [Non-trapping float-to-int Conversions] language features, which are
 [widely implemented in engines].
 
-A new Lime1 target CPU is added, -mcpu=lime1. This CPU follows the definition of
+* A new Lime1 target CPU is added, -mcpu=lime1. This CPU follows the definition of
 the Lime1 CPU [here], and enables -mmultivalue, -mmutable-globals,
 -mcall-indirect-overlong, -msign-ext, -mbulk-memory-opt, -mnontrapping-fptoint,
 and -mextended-const.
 
+* The support for the new standardized [Exception Handling] proposal is added.
+  The [legacy Exception Handling] proposal is still supported, and turned on by
+  the newly added `-wasm-use-legacy-eh` option. Given that major web browsers
+  still default to the legacy EH proposal, this option is turned on by default
+  for the moment.
+
 [Bulk Memory Operations]: https://github.com/WebAssembly/bulk-memory-operations/blob/master/proposals/bulk-memory-operations/Overview.md
 [Non-trapping float-to-int Conversions]: https://github.com/WebAssembly/spec/blob/master/proposals/nontrapping-float-to-int-conversion/Overview.md
+[Exception Handling]: https://github.com/WebAssembly/exception-handling/blob/main/proposals/exception-handling/Exceptions.md
+[legacy Exception Handling]: https://github.com/WebAssembly/exception-handling/blob/main/proposals/exception-handling/legacy/Exceptions.md
 [widely implemented in engines]: https://webassembly.org/features/
 [here]: https://github.com/WebAssembly/tool-conventions/blob/main/Lime.md#lime1