add appendleft term

[msaf9]

Description

Added a new entry for the appendleft() method under the deque module in Python.
This entry provides a description of the method, its syntax, and an example demonstrating its use.
The goal is to improve Python deque documentation by covering all major methods.

Issue Solved

Will close #7746

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.

[mamtawardhani]

Looks good for a second review! 🚀

[dakshdeepHERE]

LGTM 👍

[github-actions]

👋 @msaf9
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