Adds troubleshooting page for kubernetes

Add navigation item to global navigation

• Link to the merge request that introduced the new page: gitlab-runner!5034 (merged)
• Give the MR a descriptive title.
• Optional. Link to the review app showing the new page: https://main-runner-5034.docs.gitlab-review.app/runner/install/kubernetes_troubleshooting.html

Pipelines will fail until gitlab-runner!5034 (merged) merges.

Naming question

In comment gitlab-runner!5034 (comment 2127952462), I brought up a naming inconsistency between the displayed page title and its filename. That question ripples down to what I should name this new child page. Should it be kubernetes_troubleshooting.md, helm_troubleshooting.md, or some other option I've not thought of yet?

Related

• Related to FY25Q3 TW OKR: Refactor high visibility pages f... (technical-writing#1075) where we're tracking OKR work.
• Related to K8s install page: move troubleshooting info, ta... (gitlab-runner!5034 - merged)