Update Node 18 to reflect that it supports lib=ES2023

Node-Target-Mapping.md

@@ -24,13 +24,15 @@ To update this file, you can use [node.green](https://node.green) to map to the
 ```json
 {
   "compilerOptions": {
-    "lib": ["ES2022"],
+    "lib": ["ES2023"],
     "module": "node16",
     "target": "ES2022"
   }
 }
 ```
 
+Note: All versions of Node 18 support all ES2023 runtime features, so `lib` can be safely set to `ES2023`.
+
 #### Node 16
 
 ```json