Feat: Added deque.insert() term entry under Python deque.

[Jivi-this-side]

Description

This PR adds a new term entry for deque.insert() under the Python deque concept.

• file located at:
  content/python/concepts/deque/terms/insert/insert.md

✏️ The entry covers:

• What deque.insert() does and when to use it
• Syntax with parameter definitions and return behavior
• Example code snippets demonstrating insertion at different positions
• A live Codebyte example for practical exploration
• A set of FAQs explaining performance, index behavior, and differences with append() and appendleft()

Issue Solved

🌻 Closes #7758

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.

--------------------------------------------Thank you!!! 😃--------------------------------------------------------------

[CLAassistant]

All committers have signed the CLA.

[mamtawardhani]

Looks good for a second review! 🚀

[Radhika-okhade]

Minor changes.

[Radhika-okhade]

@Jivi-this-side The entry looks good to be merged.

[github-actions]

👋 @Jivi-this-side
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