Changed the tick marks for std::list<int> Numbers;

[ghost]

Changed the tick marks for std::list Numbers; so it displays correctly.

• 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.
• My article does not contain shortened URLs or affiliate links.

If your pull request closes a GitHub issue, replace the XXXXX below with the issue number.

Closes #XXXXX

[Manish-Giri]

Hi @ltr7

Congrats on your first pull request (PR)! 🎉

Thank you for your contribution to the page! 👍 We're happy to accept these changes and look forward to future contributions. 📝