docs: update theming example to next 15

[joshblack]

Update our theming example from Next v14 to v15.

Changelog

New

Changed

• Update examples/theming from Next v14 to Next v15

Removed

Rollout strategy

• [x] None; if selected, include a brief description as to why

This change is only to an internal example and does not affect our Public API.

[changeset-bot[bot]]

⚠️ No Changeset found

Latest commit: dab8883254cc10449d42f076ddb54e57ca3253b8

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

[github-actions[bot]]

size-limit report 📦

Path	Size
packages/react/dist/browser.esm.js	92.33 KB (0%)
packages/react/dist/browser.umd.js	92.37 KB (0%)