checkpoints continue to be readable; controlled by the `write_version`
    argument, `tf.train.Saver` now by default writes out in the new V2 format.
    It significantly reduces the peak memory required and latency incurred
    during restore.
*   Added a new library for library of matrix-free (iterative) solvers for

### Immutable Secrets and ConfigMaps (beta)

Secret and ConfigMap volumes can be marked as immutable, which significantly reduces load on the API server if there are many Secret and ConfigMap volumes in the cluster.