Add new entry for front() method under deque in C++ docs

[killjoycircuit]

👋 Hi! Thanks for reviewing my PR to Codecademy Docs! 💖

Description

This PR adds a new entry for the term front() under the deque concept in C++. The new entry explains what front() does, shows its syntax, includes an example, and provides a compilable code snippet demonstrating its use.

Issue Solved

There was no existing documentation for the front() method of deque. This entry fills that gap and helps learners understand how to access and modify the first element in a deque.

Issue Linked / Reason / Inspiration (optional)

We would like a new entry on the term front() under deque in C++. The entry is located at content/cpp/concepts/deque/terms/front/front.md.

The entry includes:

• A description of the term
• A ## Syntax section with method syntax and details
• An ## Example section demonstrating usage
• A ## Codebyte section with compilable C++ code using the codebyte/cpp fence

Type of Change

• Adding a new entry
• 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.

Thanks for your time and consideration! 😊

[CLAassistant]

All committers have signed the CLA.

[mamtawardhani]

Looks good for a second review! 🚀