Update readme

Author: bjorn3

Readme.md

@@ -104,7 +104,7 @@ See [rustc_testing.md](docs/rustc_testing.md).
 ## Not yet supported
 
 * SIMD ([tracked here](https://github.com/rust-lang/rustc_codegen_cranelift/issues/171), `std::simd` fully works, `std::arch` is partially supported)
-* Unwinding on panics ([no cranelift support](https://github.com/bytecodealliance/wasmtime/issues/1677), `-Cpanic=abort` is enabled by default)
+* Unwinding on panics for Windows and macOS (Windows uses a fundamentally different unwinding mechanism and macOS support is not implemented yet. `-Cpanic=abort` is enabled by default)
 
 ## License