Update is-power-of-two.md

[xFrann]

Fixed code error to also match comments.

Description

Improvement to an existing snippet, can also be considered bug fix

• ✨ New snippet
• 🛠 Improvement to an existing snippet
• 🐞 Bug fix
• 📖 Documentation update
• 🔧 Other (please describe):

Checklist

• [ x ] I have tested my code and verified it works as expected.
• [ x ] My code follows the style and contribution guidelines of this project.
• [ x ] Comments are added where necessary for clarity.
• [ x ] Documentation has been updated (if applicable).
• [ x ] There are no new warnings or errors from my changes.

Related Issues

Closes # No issues opened

Additional Context

Screenshots (Optional)

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