Add CODEOWNERS sections

[HerHde]

Feature Description

In GitLab, the code owners feature supports an extended syntax with sections, grouping files and dirs together. It would be nice to have this feature in Gitea, as well

[Documentation] @docs-team
docs/
README.md

[Database] @database-team @agarcia
model/db/
config/db/database-setup.md @docs-team

Screenshots

No response