[skip ci] Update README.md

Author: kateinoigakukun

README.md

@@ -45,6 +45,8 @@ You can find API documentation on the [Swift Package Index](https://swiftpackage
 |                      | [Mutable globals](https://github.com/WebAssembly/mutable-global/blob/master/proposals/mutable-global/Overview.md) | ✅ Implemented |
 |                      | [Sign-extension operators](https://github.com/WebAssembly/spec/blob/master/proposals/sign-extension-ops/Overview.md) | ✅ Implemented |
 |                      | [Non-trapping float-to-int conversions](https://github.com/WebAssembly/nontrapping-float-to-int-conversions/blob/main/proposals/nontrapping-float-to-int-conversion/Overview.md) | ✅ Implemented |
+|                      | [Memory64](https://github.com/WebAssembly/memory64/blob/main/proposals/memory64/Overview.md) | ✅ Implemented |
+|                      | [Threads and atomics](https://github.com/WebAssembly/threads/blob/master/proposals/threads/Overview.md) | 🚧 Parser implemented |
 | WASI | WASI Preview 1 | ✅ Implemented |