Re-added the mobile images to the site for mobile.

[databunnyllc]

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• [ ] I have read freeCodeCamp's contribution guidelines.
• [ ] My pull request has a descriptive title (not a vague title like Update index.md)
• [ ] My pull request targets the master branch of freeCodeCamp.
• [ ] None of my changes are plagiarized from another source without proper attribution.
• [ ] All the files I changed are in the same world language (for example: only English changes, or only Chinese changes, etc.)
• [ ] My changes do not use shortened URLs or affiliate links.

Closes #XXXXX