Add support for automated comments in stack update PRs

[thepetk]

Which area is this issue related to?

/area ci
/area registry

Issue Description

According to our LIFECYCLE.md & CONTRIBUTING.md files each Stack Update PR needs to be reviewed by the Stack Owner and the Eclipse Che team.

This needs to be clear in every PR. That said we could create an automation that notifies the PR author about our process. We could also revisit the Openshift CI automated comments and see if there's anything we could update there.

Acceptance Criteria

• Stack update PRs always include a comment that clarifies our processes

Target Odo Version

Target Odo version:

[github-actions]

This issue is stale because it has been open for 90 days with no activity. Remove stale label or comment or this will be closed in 120 days.