[Hello World]: Prefix 'docker push' with gcloud command
[Hello World]: Prefix 'docker push' with gcloud command

In order to push to the Google Container Registry the `glcoud` command
should be used as per https://cloud.google.com/container-registry/docs/#pushing_to_the_registry

aidevops/kubernetes.github.io,erictune/erictune.github.io,AlainRoy/alainroy.github.io,erictune/erictune.github.io,erictune/erictune.github.io,aidevops/kubernetes.github.io,hurf/kubernetes-docs-cn,ronaldpetty/kubernetes.github.io,rata/kubernetes.github.io,ronaldpetty/kubernetes.github.io,erictune/erictune.github.io,erictune/erictune.github.io,ronaldpetty/kubernetes.github.io,hurf/kubernetes-docs-cn,aidevops/kubernetes.github.io,rata/kubernetes.github.io,rata/kubernetes.github.io,aidevops/kubernetes.github.io,AlainRoy/alainroy.github.io,hurf/kubernetes-docs-cn,rata/kubernetes.github.io,AlainRoy/alainroy.github.io,rata/kubernetes.github.io,aidevops/kubernetes.github.io