[kubernetes/kubernetes] Pre-release v1.18.0-beta.2 - v1.18.0-beta.2

CRANK

See [kubernetes-announce@](https://groups.google.com/forum/#!forum/kubernetes-announce) and [CHANGELOG/CHANGELOG-1.18.md](https://github.com/kubernetes/kubernetes/blob/master/CHANGELOG/CHANGELOG-1.18.md#v1180-beta2) for details. SHA256 for `kubernetes.tar.gz`: `1d29a92e770bafd2b3982b0d95d2da540b2ccf3b928d3221e9ac40331ded4bc7` SHA512 for `kubernetes.tar.gz`: `3017430ca17f8a3523669b4a02c39cedfc6c48b07281bc0a67a9fbe9d76547b76f09529172cc01984765353a6134a43733b7315e0dff370bba2635dd2a6289af` Additional binary downloads are linked in the [CHANGELOG/CHANGELOG-1.18.md](https://github.com/kubernetes/kubernetes/blob/master/CHANGELOG/CHANGELOG-1.18.md#downloads-for-v1180-beta2).