What article on docs.github.com is affected?

https://docs.github.com/en/actions/guides/building-and-testing-nodejs#example-caching-dependencies

What part(s) of the article would you like to see updated?

The example that shows how to cache npm packages includes use of the npm ci command. However npm ci deletes any existing "node_modules/" directory when it starts so I think you should have npm install there instead.