docs(release): update release process

[DariuszPorowski]

Description

Clarification for release notes

Type of change

• This pull request is a minor refactor, code cleanup, test improvement, or other maintenance task and doesn't change the functionality of Radius (issue link optional).

Contributor checklist

Please verify that the PR meets the following requirements, where applicable:

• An overview of proposed schema changes is included in a linked GitHub issue.
  • Yes
  • Not applicable
• A design document PR is created in the design-notes repository, if new APIs are being introduced.
  • Yes
  • Not applicable
• The design document has been reviewed and approved by Radius maintainers/approvers.
  • Yes
  • Not applicable
• A PR for the samples repository is created, if existing samples are affected by the changes in this PR.
  • Yes
  • Not applicable
• A PR for the documentation repository is created, if the changes in this PR affect the documentation or any user facing updates are made.
  • Yes
  • Not applicable
• A PR for the recipes repository is created, if existing recipes are affected by the changes in this PR.
  • Yes
  • Not applicable

[Copilot]

Pull request overview

This PR updates the Radius release process documentation to clarify the cherry-pick workflow used across all release types (RC, final, and patch). It adds explicit step-by-step cherry-pick instructions, introduces a summary table showing what gets cherry-picked for each release type, and expands the guidance around single-commit discipline for the final release. Version placeholders are also normalized from lowercase vx.y.z to uppercase vX.Y.Z.

Changes:

• Added a new "Cherry-pick workflow" section summarizing the common pattern across all release types
• Added explicit shell commands for cherry-picking versions.yaml and optional commits onto the release branch during RC creation
• Clarified the final release flow to require a single commit (version bump + release notes) and provided detailed cherry-pick steps with branch naming conventions