This PR addresses the issue in kmesh-net/kmesh#1412

This PR introduces and documents an automated versioning workflow for our Docusaurus documentation site using GitHub Actions. The goal is to automatically create versioned documentation branches whenever a new Git tag prefixed with v (e.g., v1.2.0) is pushed to the repository.

This ensures that:

• Each released version of the product has a dedicated snapshot of its documentation.
• Users can access historical documentation via the Docusaurus version dropdown.
• Maintenance of past versions is streamlined and consistent.

How to Use:

1. Tag a release: git tag v1.2.0 && git push origin v1.2.0
2. Wait for the action to run
3. Review and merge the auto-created PR

Permissions:

• The workflow uses secrets.GITHUB_TOKEN to create branches and PRs.
• Ensure the repo allows GitHub Actions to create pull requests (default in public repos; may require approval in private/org repos).

Important Considerations:

1. Supported Tag Format:

• Tags must follow the format vX.Y.Z (e.g., v1.0.0, v2.3.4-alpha).
• Tags like release-1.0 or 1.0.0 (without v) will not trigger the workflow.

2. Multi-Language Support:

• Currently, only English (en) documentation is versioned.
• Chinese (zh) and other locales will fallback to English content for older versions, per Docusaurus default behavior.
• If localized versions are needed in the future, manual intervention or additional automation will be required.

3. Conflicts & Manual Fixes:

• If two version tags are created rapidly, race conditions may occur.
• If the PR shows unexpected changes (e.g., unrelated files), investigate possible merge drift or uncommitted local changes at time of tagging.

4. Do Not Run Locally:

• Avoid running docusaurus docs:version manually unless absolutely necessary.
• Doing so may cause conflicts with the automated flow or inconsistent version metadata.