Context switcher doc updates
Based on this issue: #409522 (closed)
Last MR to merge before we update the docs: !129843 (merged)
We will need to update the documentation. This issue is to track that work.
- Need to open MR for style guide.
- Need to open MRs to update docs.
- Don't forget this page, which has lots of changes: https://docs.gitlab.com/ee/user/search/
Edited by Suzanne Selhorn