docs(TreeView): Update examples

[silvalaura]

Issue: none

What I did

initialExpandedItems example was using the wrong ID so the items were not expanding as expected.

Checklist

• [x] changeset has been added
• [x] Pull request description is descriptive
• [x] I have made corresponding changes to the documentation
• [ ] New and existing unit tests pass locally with my changes
• [ ] I have added tests that prove my fix is effective or that my feature works

How to test

Confirm all examples in tree view docs behave as expected

[changeset-bot[bot]]

🦋 Changeset detected

Latest commit: ffeaf9f67f008d18c708723a263c422527a3ead7

The changes in this PR will be included in the next version bump.

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