[Term Entry] C++ Unordered-sets: swap()

[sthuthi21]

Description

[Term Entry] C++ Unordered-sets: swap()

Issue Solved

Closes #8045

Type of Change

• Adding a new entry

Checklist

• All writings are my own.
• My entry follows 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 my entry 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.

[CLAassistant]

All committers have signed the CLA.

[Copilot]

Pull request overview

This PR adds comprehensive documentation for the swap() method used with C++ unordered sets, providing both member and non-member function usage patterns.

Key Changes:

• Documents both member function and non-member function syntax for swapping unordered sets
• Includes two complete code examples demonstrating swap functionality with integer and string unordered sets
• Explains constant-time complexity and iterator validity behavior after swapping

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[mamtawardhani]

The PR looks good for a second review! 🚀