fix: node 16.5+

README.md

@@ -162,7 +162,7 @@ Implements [fetch](https://fetch.spec.whatwg.org/#fetch-method).
 * https://developer.mozilla.org/en-US/docs/Web/API/WindowOrWorkerGlobalScope/fetch
 * https://fetch.spec.whatwg.org/#fetch-method
 
-Only supported on Node 16+.
+Only supported on Node 16.5+.
 
 This is [experimental](https://nodejs.org/api/documentation.html#documentation_stability_index) and is not yet fully compliant with the Fetch Standard. We plan to ship breaking changes to this feature until it is out of experimental.