chore(docs): Update Vue label to 'vue 3' in playgrounds index

[mfranzke]

Proposed changes

Types of changes

• Bugfix (non-breaking change that fixes an issue)
• New feature (non-breaking change which adds functionality)
• Refactoring (improvements to existing components or architectural decisions)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Update (if none of the other choices apply)

Further comments

🔭🐙🐈 Test this branch here: https://design-system.deutschebahn.com/core-web/review/mfranzke-patch-1

[changeset-bot]

⚠️ No Changeset found

Latest commit: 1bf1922

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types

Click here to learn what changesets are, and how to add one.

Click here if you're a maintainer who wants to add a changeset to this PR