Update "Support" menu links in the main navigation bar.
This makes a few small tweaks to the "Support" menu links in the main navigation bar at https://about.gitlab.com/:
- It adds trailing slashes to two of the link URLs for consistency and to avoid redirection (one of them will still redirect to a locale-specific URL).
- It changes "Contact support" to "Contact Support" because "Support" is the short version of a proper noun ("Support Department" or "Support Team").
- It changes "Caring for Customers" to "Caring for customers" because the main navigation menu items mostly appear in sentence case (with the exception of the "Product" menu, which uses sentence case, title case, and something between the two).