Create documentation for 'align-content' flexbox property

[Tibnaamer]

Added documentation for the 'align-content' property in flexbox, including its syntax, effects, and examples.

Description

Created a new entry on the term align-content under flexbox, created an align-content.md file - New to Github, thought this would be a good place to start,

Issue Solved

[Term Entry] CSS Flexbox: align-content #8196

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.