Add margin block term

[mawowo67]

Description

Added a new term entry for margin-block in CSS under:

content/css/concepts/margins/terms/margin-block/margin-block.md

This entry includes:

• A description of the property.
• Syntax section with details for <start> and <end>.
• Example section with CSS code block demonstrating usage.
• Notes explaining the advantages of using logical properties and supporting different writing modes.

Issue Solved

Closes #8216

Type of Change

• Adding a new entry
• Editing an existing entry (fixing a typo, bug, issues, etc)
• Updating the documentation

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.

[mamtawardhani]

Hey @mawowo67, this entry does not follow the Codecademy Standards and it is missing multiple things:

• meta data is missing at the beginning
• the introdocution needs to follow the standards
• Syntax should be wrapped in pseudo block
• The parameters should be under the Parameters: heading
• Example is missing description
• Output image of the example needs to be attached in the PR. Please place it in the media folder in docs.

You can refer to the existing PRs of CSS to get a clear picture. Once the changes are done, let me know! 😄