docs: Add documentation for 7 new programming languages

Update documentation for PR #275 extended language detection:
- CHANGELOG.md: Add comprehensive section for new languages
- language_detector.py: Update docstrings from 20+ to 27+ languages

New languages:
- Dart (Flutter framework)
- Scala (pattern matching, case classes)
- SCSS/SASS (CSS preprocessors)
- Elixir (functional, pipe operator)
- Lua (game scripting)
- Perl (text processing)

70 regex patterns with confidence scoring (0.6-0.8+ thresholds)
7 new tests, 30/30 passing (100%)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/skill_seekers/cli/language_detector.py

@@ -3,7 +3,7 @@
 Unified Language Detection for Code Blocks
 
 Provides confidence-based language detection for documentation scrapers.
-Supports 20+ programming languages with weighted pattern matching.
+Supports 27+ programming languages with weighted pattern matching.
 
 Author: Skill Seekers Project
 """
@@ -505,7 +505,7 @@ class LanguageDetector:
     """
     Unified confidence-based language detection for code blocks.
 
-    Supports 20+ programming languages with weighted pattern matching.
+    Supports 27+ programming languages with weighted pattern matching.
     Uses two-stage detection:
     1. CSS class extraction (high confidence = 1.0)
     2. Pattern-based heuristics with confidence scoring (0.0-1.0)