Add fuzzy to the list of advanced search syntax options

What does this MR do and why?

Updates the advanced search syntax helper and documentation to include the fuzzy operator ~ as part of advanced search syntax. Also adds a section to the Syntax options for how user search works.

Screenshots or screen recordings

Syntax options:

Documentation:

How to set up and validate locally

N/A

MR acceptance checklist

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Related to #388409 (closed)