Add newly split user token topic to global navigation

What does this MR do and why?

For: technical-writing#1075, and as a companion to gitlab!165596 (merged), add newly split user token topic to global navigation.

Merge request acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this merge request.