chore(git-node): add make lint-md reminder

After two consecutive releases in which I mistakely pushed a broken
release commit to main, I'm convinced that the process needs
improvement.

This changeset proposes to add a reminder to `git node release promote`
to lint markdown files prior to pushing branches to upstream remote.

Refs: nodejs/node@a344300
Refs: nodejs/node#56508

lib/promote_release.js

@@ -195,6 +195,12 @@ export default class ReleasePromotion extends Session {
       }
     }
 
+    cli.separator();
+    cli.warn('Reminder: Lint markdown files');
+    cli.info('You might need to amend the commit if there are issues:');
+    cli.info('make lint-md');
+    cli.separator();
+
     // Push to the remote the release tag, and default, release, and staging branch.
     await this.pushToRemote(workingOnNewReleaseCommit);