Add max_size.md term entry for C++ Sets

[hevolx]

Title

Add max_size.md term entry for C++ Sets with description, syntax, example, and codebyte

Description

This pull request adds a new term entry for the max_size() method under C++ Sets, located in content/cpp/concepts/sets/terms/max_size/max_size.md. The content follows Codecademy’s term entry template, content standards, and markdown style guide. The motivation for this change is to provide comprehensive documentation for the max_size() method, enhancing the C++ Sets concept entry.

Issue Solved

Closes #7176

Type of Change

• Adding a new entry
• Editing an existing entry (fixing a typo, bug, issues, etc)
• Updating the documentation

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.