docs(seed-docs): TextField 스펙 변경

[junghyeonsu]

• medium, small 일 때 fontSize 변경
• small 일 때 높이값 변경

[changeset-bot]

⚠️ No Changeset found

Latest commit: e74f064

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.

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[github-actions]

Deploy Seed Docs Alpha Pages / Deploy Seed Docs (push) CI가 성공적으로 끝나면 해당 링크로 이동해서 preview를 확인해요 -> https://dash.cloudflare.com/aad5c82543cd1f267b89737d0f56405e/pages/view/seed-design