mention support for URL/URLSearchParams/Temporal in README

Author: Rich-Harris

README.md

@@ -10,6 +10,8 @@ Like `JSON.stringify`, but handles
 - `Map` and `Set`
 - `BigInt`
 - `ArrayBuffer` and Typed Arrays
+- `URL` and `URLSearchParams`
+- `Temporal`
 - custom types via replacers, reducers and revivers
 
 Try it out [here](https://svelte.dev/repl/138d70def7a748ce9eda736ef1c71239?version=3.49.0).