Update Japanese to support Docsy-style menus

[lmktfy]

Description

Update the front matter for Japanese pages so that if we align more with Docsy, the top nav still works how we want. Currently, the top nav sections are hard coded:

• website/layouts/partials/navbar.html

  Line 28 in c07ffdf

  {{ $sections := slice "docs" "blog" "training" "careers" "partners" "community" }}

• website/layouts/404.html

  Line 9 in c07ffdf

  {{ $sections := slice "docs" "blog" "training" "careers" "partners" "community" }}

Original vs preview (no visible difference; this is an enabling change)

Issue

Helps with issues #41171 and #50228

[netlify]

✅ Pull request preview available for checking

Built without sensitive environment variables

Name	Link
🔨 Latest commit	436f1e2
🔍 Latest deploy log	https://app.netlify.com/projects/kubernetes-io-main-staging/deploys/689ba94fd81b1f0008ec88e2
😎 Deploy Preview	https://deploy-preview-51875--kubernetes-io-main-staging.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify project configuration.

[Okabe-Junya]

Thanks, almost LGTM

Please check t-inu's comment

[Okabe-Junya]

/assign
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Okabe-Junya

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• content/ja/OWNERS [Okabe-Junya]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[t-inu]

Thanks
/lgtm

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: a53843b06d0720e03c5c2aa93f8133157b73d439