Rename and reorder the "CEO" section on the handbook home page.
This renames the "CEO" heading to "Company", reorders the items in that section to emphasize the Values, Communication, and Handbook sections, and changes the "CEO" link text to "CEO Readme" at https://about.gitlab.com/handbook/.
Note: This does not change any of the content on the linked pages—only the links on the handbook home page. We can iterate on those things—and further on the handbook home page—in separate merge requests.