dbc: clarify double sign-in requirement

Signed-off-by: David Karlsson <35727626+dvdksn@users.noreply.github.com>

Author: dvdksn

content/manuals/build-cloud/builder-settings.md

@@ -70,10 +70,9 @@ internal package repositories for npm or PyPI, use [build secrets](/manuals/buil
 to authenticate during the build. For internal OCI registries, use `docker
 login` to authenticate before building.
 
-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.
+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).
 
 ```console
 $ echo $DOCKER_PAT | docker login docker.io -u <username> --password-stdin