Runner improve technical accuracy OKR: Rearrange runner docs

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• Link to the merge request that introduced the new page: https://gitlab.com/gitlab-com/gitlab-OKRs/-/work_items/10049
• Give the MR a descriptive title.
• Optional. Link to the review app showing the new page: - https://nav-runner-accuracy-okr.docs.gitlab-review.app/runner/ - https://nav-runner-accuracy-okr.docs.gitlab-review.app/ee/ci/runners/ - https://nav-runner-accuracy-okr.docs.gitlab-review.app/runner/install/ - https://nav-runner-accuracy-okr.docs.gitlab-review.app/runner/configuration/