HTML5Rocks was a content site run by Google. Its content lives on at Web Fundamentals and web.dev. Chrome-specific content can be found at Chrome Developers.
HTML5Rocks is not deployed automatically.
If you make a change, you'll need to deploy it.
You can just run gcloud
from this folder (there's no build step):
$ gcloud app deploy --project html5rocks-hrd --no-promote ./app.yaml
This will deploy to a unique version and hostname but not take over serving yet. Check it works with your browser, then migrate all traffic to the new version from the Cloud Console.
If you need access to do this, ask in team chat or ping a lead.
If you're removing content and want to add a redirect, add it to the "_redirects.yaml" file. Changes to this file need the site to be redeployed as described above.