[Term Entry] C++ Unordered-sets: insert() (#8023)

[smp242]

• Path: content/cpp/concepts/unordered-set/terms/insert/unordered_set_insert.md

Description

• Adds new term entry for unordered_set::insert()

Issue Solved

Type of Change

• Includes syntax, parameters, return value, and two examples
• Adds interactive Codebyte (word filter) and brief note on hash tables & collisions
• Adds short rvalue/move-semantics blurb and FAQ

Checklist

• [x] All writings are my own.
• [x] My entry follows the Codecademy Docs style guide.
• [x] My changes generate no new warnings.
• [x] I have performed a self-review of my own writing and code.
• [x] I have checked my entry and corrected any misspellings.
• [x] I have made corresponding changes to the documentation if needed.
• [x] I have confirmed my changes are not being pushed from my forked main branch.
• [x] I have confirmed that I'm pushing from a new branch named after the changes I'm making.
• [x] I have linked any issues that are relevant to this PR in the Issues Solved section.

[CLAassistant]

All committers have signed the CLA.

[smp242]

Looks good for a second review! 🚀

Cool. Sorry to need a little hand holding as I've never done this before. Do I have a next step? Or do you guys take it from here?