Docs: Fix typo in "The block wrapper" document

[t-hamano]

I fixed a typo that I happened to find.

• ❌ accesibility
• ✅ accessibility

Due to my code editor settings, some trailing spaces are removed, but this should be fine.

[github-actions]

Flaky tests detected in 8272b1a.
Some tests passed with failed attempts. The failures may not be related to this commit but are still reported for visibility. See the documentation for more information.

🔍 Workflow run URL: https://github.com/WordPress/gutenberg/actions/runs/7622104795
📝 Reported issues:

• [Flaky Test] the event listener is removed when the element is removed #57983 in /test/e2e/specs/interactivity/directive-on-document.spec.ts