Explicitly defined UX reviewer instructions

What does this MR do and why?

Added more details on UX reviewer needs for MR reviews in an attempt to remove ambiguity on UX department guidelines.

Screenshots or screen recordings

Screenshots are required for UI changes, and strongly recommended for all other merge requests.

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

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.