KEP Reviewers/Approvers vs KEP Process Owners

[Stephen Augustus]

Hey SIG PM / SIG Arch--

Now that we've distinguished between:

• Who reviews/approves KEPs (SIG Architecture)
  
• Who stewards the KEP process (SIG PM)

I'd like the enhancements repo to reflect that in OWNERS. I've opened a PR to do that: https://github.com/kubernetes/enhancements/pull/728
This should push the needle forward on reducing the cognitive burden on KEP reviewers.

For now, kep-reviewers and kep-approvers are the same set of people.
Let me know (on the PR) if there are additional people I should include.

Additionally, what are your thoughts on having GitHub teams for each group? Say:

• @kubernetes/kep-reviews (kep-approvers + kep-reviewers)
  
• @kubernetes/kep-process (kep-process-approvers + kep-process-reviewers)
  

-- Stephen