ci: add wf to create GH release for the examples repo

[tbouffard]

Relates to process-analytics/bpmn-visualization-examples#375

### Tasks
- [x] update README: list workflow
- [x] add body

[github-actions]

♻️ PR Preview 4df7897 has been successfully destroyed since this PR has been closed.

_{🤖 By surge-preview}

[tbouffard]

ℹ️ Completed by #312
✔️ GH release successfully created: https://github.com/process-analytics/github-actions-playground/releases/tag/v3.0.3 (in draft, published manually)

• https://github.com/process-analytics/github-actions-playground/actions/runs/7444301475/job/20250481653

Run ncipollo/release-action@v1
  with:
    body: Examples for [[email protected]](https://github.com/process-analytics/bpmn-visualization-js/releases/tag/v3.0.3).
  Live examples are available for [3.0.3](https://cdn.statically.io/gh/process-analytics/bpmn-visualization-examples/v3.0.3/examples/index.html).
  
    draft: true
    generateReleaseNotes: true
    name: 3.0.3
    makeLatest: legacy
    omitBody: false
    omitBodyDuringUpdate: false
    omitDraftDuringUpdate: false
    omitName: false
    omitNameDuringUpdate: false
    omitPrereleaseDuringUpdate: false
    removeArtifacts: false
    replacesArtifacts: true
    skipIfReleaseExists: false
    token: ***
    updateOnlyUnreleased: false
  env:
    RELEASE_VERSION: 3.0.3
    TAG: v3.0.3