Update alpha API to beta

[bswartz]

What type of PR is this?
/kind api-change

What this PR does / why we need it:
Change alpha API to beta

Does this PR introduce a user-facing change?:

Renamed v1alpha1 API to v1beta1. The API is the same, but users must use the new version.

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: bswartz

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [bswartz]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[xing-yang]

/assign

[chrishenzie]

/lgtm

[chrishenzie]

I didn't expect that to go through without approval, apologies @xing-yang

[bswartz]

I didn't expect that to go through without approval, apologies @xing-yang

Looks like something causes me to auto-approve my own PRs. I wonder if that can be reversed.

[bswartz]

@xing-yang Any feedback/concerns you have I can address in a new PR, just let me know.

[xing-yang]

@chrishenzie @bswartz no worries. I'll take a look. If I have comments, Ben can address with a followup PR.

[xing-yang]

Should line 8 be updated?

api-approved.kubernetes.io: https://github.com/kubernetes/enhancements/pull/2056