feat(docs): remove unnecessary type casts

[PiotrekPKP]

✅ Checklist

• I have followed every step in the contributing guide (updated 2022-10-06).
• The PR title follows the convention we established conventional-commit
• I performed a functional test on my final commit

---

Changelog

• removed type casts from sidebar array using spread which makes TS happy
• removed Entry type and used inference instead
• added OuterHeaders return type to make sure function returns correct value

💯

[changeset-bot]

⚠️ No Changeset found

Latest commit: 12872f1

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

[vercel]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name	Status	Preview	Comments	Updated (UTC)
create-t3-app	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Apr 2, 2023 11:55am

[github-actions]

Running Lighthouse audit...