Remove card-layout from N+ landing page

[lamATnginx]

Proposed changes

Remove card-layout

Checklist

Before sharing this pull request, I completed the following checklist:

• I read the Contributing guidelines
• My branch adheres to the Git conventions
• My content changes adhere to the F5 NGINX Documentation style guide
• If my changes involve potentially sensitive information¹, I have assessed the possible impact
• I have waited to ensure my changes pass tests, and addressed any discovered issues

Footnotes

1. Potentially sensitive information includes personally identify information (PII), authentication credentials, and live URLs. Refer to the style guide for guidance about placeholder content. ↩

[mjang]

IIRC, Jack noted in a previous PR that the broken build in PRs against the current mainframe branch are -- not an issue.

[lamATnginx]

IIRC, Jack noted in a previous PR that the broken build in PRs against the current mainframe branch are -- not an issue.

We removed card-layout in the mainframe branch of the theme so this change is updating the landing page for it. We didn't update it on main branch theme cuz it can lead to some merge conflicts that overly complicate mainframe branch.