[RFC]: add help modal for how to use side menu filter

[kgryte]

Description

This RFC proposes adding a help modal/popover for how to use the side menu filter.

Currently, the side menu filter supports regular expression queries, but this is not obvious to a user. We should add support for displaying a how-to guide with example search queries.

Related Issues

No.

Questions

No.

Other

No.

Checklist

• [X] I have read and understood the Code of Conduct.
• [X] Searched for existing issues and pull requests.
• [X] The issue name begins with RFC:.