Update logomark in docs

[rezrah]

Summary

Towards https://github.com/github/brand-marketing-design/issues/2674

Updates the invertocat logo to the new 2026 branding.

List of notable changes:

Only affects docs meta data, as all other instances are either pointing at:

• Octicons
• Dotcom CDN assets

What should reviewers focus on?

• Review file diffs

Contributor checklist:

• All new and existing CI checks pass
• Tests prove that the feature works and covers both happy and unhappy paths
• Any drop in coverage, breaking changes or regressions have been documented above
• UI Changes contain new visual snapshots (generated by adding update snapshots label to the PR)
• All developer debugging and non-functional logging has been removed
• Related issues have been referenced in the PR description

Reviewer checklist:

• Check that pull request and proposed changes adhere to our contribution guidelines and code of conduct
• Check that tests prove the feature works and covers both happy and unhappy paths
• Check that there aren't other open Pull Requests for the same update/change

Screenshots:

Please try to provide before and after screenshots or videos

Before	After

[changeset-bot]

⚠️ No Changeset found

Latest commit: 55ccb6b

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

[Copilot]

Copilot wasn't able to review any files in this pull request.

Files not reviewed (1)

• apps/next-docs/package-lock.json: Language not supported

[github-actions]

🟢 No design token changes found

[github-actions]

🟢 No visual differences found

Our visual comparison tests did not find any differences in the UI.