feat: added the cross cluster ui docs

[WriteMayur]

This PR adds the new cross-cluster UI docs.
We have received this PR #22368 from PM however due to CLA check is failing multiple time even we had signed the CLA hence creating this new PR and closing the other PR.

[github-actions]

Hi @WriteMayur 👋

Thanks for your pull request! Your PR is in a queue, and a writer will take a look soon. We generally publish small edits within one business day, and larger edits within three days.

Please ensure the propsed changes look good by building it first in your local environment. Refer to this contribution guide to get the site up and running in your local.

If you really require a preview url, reach out to one of the writers and they will generate one for you.

[WriteMayur]

netlify build

[github-actions]

🚀 Netlify Preview Building!

If the build is successful, the preview for this pull request will be available at the following URL (usually takes 10-20 minutes):

https://k8s-cross-ui--docs-website-netlify.netlify.app

[github-actions]

[!NOTE]

Our Vale automated writing feedback tool has suggestions for this PR. You can view these suggestions in the Files changed tab. If you're not a New Relic docs writer, we'll review any comments and you don't need to take any action (though feel free to make edits if you like!).

[PallaviWrite]

LGTM