oneTBB - Document existing public CI and requirements

[rodburns]

Document the public CI infrastructure available for the oneTBB project.
Document requirements for public CI in order to confidently accept contributions from the community.

Fork the repo and add information to this page https://github.com/uxlfoundation/open-source-working-group/blob/main/project-infrastructure/project-ci-documentation.md

Acceptance Criteria:
Merged PR with public CI information complete