fix: convert section H1 tags to H2 for proper heading hierarchy

[gyanranjanpanda]

Fixes aboutcode-org/aboutcode#227

Changes

• Converted "AboutCode Projects Overview" from H1 to H2
• Converted "Supporters" from H1 to H2
• Ensures single H1 per page for accessibility compliance

Impact

• ✅ WCAG 2.1 compliant (Success Criterion 1.3.1)
• ✅ Improved SEO (single primary heading)
• ✅ Better screen reader navigation
• ✅ Proper semantic HTML structure

Verification

• Built successfully with npm
• Tested locally at http://localhost:3000/www.aboutcode.org/
• Verified single H1 tag via DevTools JavaScript
• Confirmed proper heading hierarchy (H1 → H2 → H3)

Testing Results

JavaScript verification confirmed exactly 1 H1 tag on the homepage:

• H1: "Welcome to AboutCode.org" (primary heading)
• H2: "AboutCode Projects Overview" (converted from H1)
• H2: "Supporters" (converted from H1)