Code Owners File in `.github/`

[devlinjunker]

Is your feature request related to a problem? Please describe:
Provide example of CODEOWNERS file

Describe the solution:
Add CODEOWNERS file to .github/ directory

Describe alternatives you've considered:
N/A

Links/Additional context:
https://docs.github.com/en/free-pro-team@latest/articles/about-code-owners

Testing:

• Test that PRs with referenced code owners are notified?

[devlinjunker]

upmerge to https://github.com/devlinjunker/template.github when complete