Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Add README and LICENSE to staging repos

Addresses https://github.com/kubernetes/kubernetes/issues/54398.

We should use the staging files instead of having some files
authoritative in the external repo. Otherwise, we complicate the
publishing process as it has to know which files come from the latter.

`README.md` and `LICENSE` are authoritative in external repos.
We should move them to staging.

**Release note**:

```release-note
NONE
```