Meta: Add Node.js bug link to PR template

Per the discussion in nodejs/node#33315,
Node.js would like to have bugs filed whenever there is a normative spec
change. Make sure this is done by adding an item to the PR template.

PULL_REQUEST_TEMPLATE.md

@@ -10,6 +10,7 @@ Thank you for contributing to the URL Standard! Please describe the change you a
 - [ ] [Implementation bugs](https://github.com/whatwg/meta/blob/master/MAINTAINERS.md#handling-pull-requests) are filed:
    * Chrome: …
    * Firefox: …
+   * Node.js: …
    * Safari: …
 
 (See [WHATWG Working Mode: Changes](https://whatwg.org/working-mode#changes) for more details.)