[Edit] Logo: Remove external link, replace it with content

[AnamolR]

Description

This PR updates the existing Logo entry in the uiux/concepts/ section to include two new sections: What a Logo Communicates and Variations and Formats.

Markdown file: logo.md
The update replaces external brand examples with structured content that follows Codecademy Docs guidelines, and expands on how logos communicate tone, values, and adaptability across formats. These additions improve the conceptual depth and practical value of the entry for learners and designers alike.

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.

Issues Solved

closes #6684

[mamtawardhani]

Hey @AnamolR please create an issue for this, thank you!

[mamtawardhani]

Looks good for a second round of review! 🚀