Add DivRem() method to C# Math Functions

[ylevental]

Description

This PR adds documentation for the Math.DivRem() method to C# Math Functions. The entry includes:

• A description of the method
• Syntax section with parameter details
• Example section demonstrating basic usage
• Codebyte example with multiple use cases (positive numbers, long integers, and negative dividends)

Issue Solved

Closes #7949

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.

[mamtawardhani]

Looks good for a second review! 🚀