[docs-scanner] Confusing explanation of double authentication in CI setup

[docker-agent]

File: content/manuals/build-cloud/ci.md

Issue

The documentation contains a confusing explanation about why users need to authenticate twice:

Note that if you use a private registry that requires authentication, you will
need to authenticate with docker login twice before building. This is because
the cloud builder needs to authenticate with Docker to use the cloud builder,
and then again to authenticate with the private registry.

The phrase "authenticate with Docker to use the cloud builder" is unclear. The example shows:

$ echo $DOCKER_PAT | docker login docker.io -u <username> --password-stdin
$ echo $REGISTRY_PASSWORD | docker login registry.example.com -u <username> --password-stdin

This suggests the first login is to Docker Hub (not "to use the cloud builder"), and the second is to the private registry.

Suggested fix

Clarify the explanation to be more precise about what each authentication step accomplishes:

If you use a private registry that requires authentication, you need to authenticate twice before building: once to Docker Hub (to access Docker Build Cloud), and once to your private registry (to push/pull images).

---

Found by nightly documentation freshness scanner