feat(stackblitz): add stackblitz project

[itsacoyote]

Types of changes

• [ ] Bug fix (a non-breaking change which fixes an issue)
• [x] New feature (a non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Description

Resolves #137 Create a stackblitz directory and set up the Stackblitz demo that is in https://stackblitz.com/edit/github-epeint?file=app.vue Update the README with a new Stackblitz link for preview.

Checklist:

• [ ] My change requires a change to the documentation.
• [x] I have updated the documentation accordingly.
• [ ] I have added tests to cover my changes (if not applicable, please state why)