Add help text for files with code owners

What does this MR do and why?

Adds a popover containing help text to files with code owners.

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Open a file with codeowners
2. The codeowners section should have a help button to trigger a popover with text and a link to the docs.

MR 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 MR.

Related to #258569 (closed)