Context

CNTRLPLANE-2531 adds documentation preview builds for PRs. However, when a PR with docs changes is merged, the production documentation site (hypershift.pages.dev) is not automatically updated.

Acceptance Criteria

• When a PR with docs/ changes is merged to main, a postsubmit job triggers automatically
• The job builds MkDocs documentation and deploys to the production Cloudflare Pages site
• A comment is posted on the merged PR confirming the docs are now live at https://hypershift.pages.dev

Implementation

Add postsubmit CI configuration to openshift/release repository:

• Reuse hypershift-docs-build step from CNTRLPLANE-2531
• Create hypershift-docs-deploy-cloudflare-production step (deploys to main branch)
• Create hypershift-docs-publish-comment step (posts "now live" comment)
• Add postsubmit job to hypershift ci-operator config