docs: C++ Unordered-sets: max_bucket_count() (#8077)

[fawez9]

Description

Added comprehensive documentation for the max_bucket_count() method in C++ unordered_set. The entry includes:

• Detailed description of the method
• Syntax section with return value details
• Practical example demonstrating usage
• Interactive codebyte example showing comparison with current bucket count

Issue Solved

Closes #[8077]

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.

[fawez9]

@mamtawardhani I've finished the work could you please check it and tell me if anything needed !!
Thank you !