Improve CODEOWNERS adoption across the repository

[timflannagan]

Do you have a suggestion for code improvement or tracking existing technical debt? Please describe.

This is a proposal for adopting the existing .github/CODEOWNERS file for broader usage throughout the repo. Right now, there's only a couple of entries -- name the solo-io/docs team -- that are no longer relevant to this organization.

Describe the solution you'd like

Evaluate the limited adoption for CODEOWNERS usage to make the code review process more streamlined over time.

Additional Context

As we continue bootstrapping this repository, I don't think there's any urgency in tackling this right now, but valuable over time.