[Edit]: Add Image Example of User Persona

[AnamolR]

Description

This PR updates the existing Persona entry in the uiux/concepts/persona/ section to add an example image of user persona.

The content itself remains unchanged in meaning or structure. This edit improves the richness of the content with this visual example of the topic.

Markdown file: persona.md

Issues Solved

Closes #6599

Type of Change

Editing an existing entry (fixing a typo, bug, issues, etc)

Checklist

• All writings are my own.
• My edits follow the Codecademy Docs style guide.
• My changes generate no new warnings.
• I have performed a self-review of my own writing and code.
• I have checked the updated content and corrected any misspellings.
• I have made corresponding changes to the documentation if needed.
• I have confirmed my changes are not being pushed from my forked main branch.
• I have confirmed that I'm pushing from a new branch named after the changes I'm making.
• I have linked any issues that are relevant to this PR in the Issues Solved section.