Add Introduction entry to table of contents

[ajeetchaulagain]

Prepend a synthetic Introduction item to the TOC that links to the post title area. Clicking it scrolls to the page top so the full heading is visible above the sticky nav.

This pull request improves the Table of Contents (ToC) functionality and refines content rendering in blog posts. The main changes ensure that the "Introduction" section is consistently recognized and handled in the ToC, enhance scrolling behavior, and update some styling and content rendering for clarity.

Table of Contents improvements:

• The "Introduction" section is now explicitly included as a heading in the ToC by selecting elements with id="introduction" in addition to h2 and h3 tags, and assigning it a fixed label and heading level (level: 2). [1] [2]
• Clicking the "Introduction" item in the ToC smoothly scrolls to the top of the page, ensuring a consistent user experience.
• The blog post header now has id="introduction" to enable correct ToC linking and scrolling.

Styling updates:

• Updated the image wrapper margin in the Markdown renderer to use vertical spacing utility for consistent spacing around responsive images. [1] [2]

Content rendering fix:

• Removed an unnecessary heading level from an image caption in the NestJS AWS Lambda CDK deployment guide for cleaner markdown rendering.

[github-actions]

Playwright test results

 30 passed

Details

 30 tests across 2 suites
 47.6 seconds
 ea86d2b