style: improve header layout and content

[herrschmidt]

Changes

Layout

• Moved subtitle below title for better readability
• Added proper spacing between title and subtitle
• Improved vertical rhythm with consistent margins

Content

• Fixed capitalization of document types (PDF, DOCX, HTML)
• Improved readability of supported formats list
• Reworded description to be clearer and more structured

Before

<div class="flex items-baseline gap-4 mb-4">
    <h2>Magic Markdown</h2>
    <p>From any document...</p>
</div>
<p>Supports PDFs, scans / images, Docx, Html and PowerPoint documents.</p>

After

<div class="mb-4">
    <h2 class="mb-2">Magic Markdown</h2>
    <p>From any document...</p>
</div>
<p>Supports PDF, DOCX and HTML documents, scans / images and PowerPoint presentations.</p>