feat: Validate keywords/search terms frontmatter

[markcheret]

Description

Add validation for SEO keywords and search terms in frontmatter to improve discoverability.

Requirements

• Check for keywords or seo_keywords field
• Validate keyword count (3-10 recommended)
• Detect keyword stuffing (too many keywords)
• Warn if keywords duplicate title/description content
• Check keyword format (comma-separated or array)

Use Cases

• SEO optimization for documentation
• Internal search improvement
• Content indexing and taxonomy

Suggested Implementation

• Optional validation (not all sites use keyword meta tags)
• Quality checks: length, relevance, duplication
• Integration with tags validation (avoid redundancy)

Example Configuration

frontmatter:
  keywords:
    min_count: 3
    max_count: 10
    warn_duplicates: true
    max_keyword_length: 30

Note

Modern SEO relies less on explicit keywords meta tags, but they're still useful for internal search and content organization.