TEP-0079: Catalog Support Tiers - Ownership and Maintenance

In #599, we added the
proposal for "Ownership and Maintenance" in [TEP-0079][tep-0079].

Since then, there have been significant changes to the Catalog:
- [TEP-0110][tep-0110]: Decouple Tekton Catalog Organization
from Resource Reference
- [TEP-0115][tep-0115]: Tekton Catalog Git-Based Versioning

In this change, we update [TEP-0079][tep-0079] to align with
[TEP-0110][tep-0110] and [TEP-0115][tep-0115].

/kind tep

[tep-0079]: https://github.com/tektoncd/community/blob/main/teps/0079-tekton-catalog-support-tiers.md
[tep-0110]: https://github.com/tektoncd/community/blob/main/teps/0110-decouple-catalog-organization-and-reference.md
[tep-0115]: https://github.com/tektoncd/community/blob/main/teps/0115-tekton-catalog-git-based-versioning.md