### Production images moved to community control

As of Kuberenetes v1.19, Kubernetes container images are stored on a community-controlled storage bucket, 
located at `{asia,eu,us}.gcr.io/k8s-artifacts-prod`. The `k8s.gcr.io` vanity domain has been updated 
to this new bucket. This brings production artifacts under community control.

### KubeSchedulerConfiguration graduates to Beta

*   TensorBoard disables all runs by default if there are more than 40 runs.
*   Removed old doc generator code.
*   GCS file system integration now supports domain buckets, e.g
    gs://bucket.domain.com/path.
*   Add `tf.summary.text` for outputting text to TensorBoard.
*   The "run" command of tfdbg's command-line interface now supports filtering