Description

This PR adds a new term entry for the CSS margin-inline-start property under the margins concept.

The new file created:
content/css/concepts/margins/terms/margin-inline-start/margin-inline-start.md

The entry includes:

• A description explaining how the logical inline start margin works
• A Syntax section outlining accepted values
• An Example section demonstrating usage and how it adapts to writing direction

This addition improves documentation coverage for logical margin properties in CSS.

Issue Solved

Closes #8213

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.