Update documentation to v1.1.20 with current features

- Updated all version references to 1.1.20
- Updated WordPress requirement to 6.0+ (tested up to 6.9.x)
- Updated WooCommerce requirement to 8.0+ (tested up to 10.x)
- Added comprehensive file structure showing Twig templates
- Added WooCommerce Blocks compatibility documentation
- Added tier labels feature documentation (v1.1.7)
- Added quantity restrictions feature documentation (v1.1.0)
- Added new usage examples for tier labels and quantity restrictions
- Updated INSTALLATION.md with complete directory structure
- Updated README.md with current version changelog
- Updated QUICKSTART.md with 8 pro tips including new features
- Updated USAGE_EXAMPLES.md with 6 complete examples
- Documented WooCommerce Blocks support and v1.1.20 critical fix

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

INSTALLATION.md

@@ -90,8 +90,8 @@ After activation, you should see:
 
 Before installation, verify:
 
-- ✓ WordPress 5.8 or higher
-- ✓ WooCommerce 5.0 or higher installed and activated
+- ✓ WordPress 6.0 or higher (tested up to 6.9.x)
+- ✓ WooCommerce 8.0 or higher (tested up to 10.x) installed and activated
 - ✓ PHP 7.4 or higher
 - ✓ Write permissions in `/wp-content/plugins/` directory
 
@@ -153,16 +153,34 @@ wp-content/
         ├── USAGE_EXAMPLES.md
         ├── includes/
         │   ├── class-wc-tpp-admin.php
+        │   ├── class-wc-tpp-settings.php
         │   ├── class-wc-tpp-cart.php
         │   ├── class-wc-tpp-frontend.php
-        │   └── class-wc-tpp-product-meta.php
-        └── assets/
-            ├── css/
-            │   ├── admin.css
-            │   └── frontend.css
-            └── js/
-                ├── admin.js
-                └── frontend.js
+        │   ├── class-wc-tpp-product-meta.php
+        │   └── class-wc-tpp-template-loader.php
+        ├── templates/
+        │   ├── admin/
+        │   │   ├── tier-row.twig
+        │   │   └── package-row.twig
+        │   └── frontend/
+        │       ├── pricing-table.twig
+        │       ├── tier-pricing-table.twig
+        │       └── package-pricing-display.twig
+        ├── assets/
+        │   ├── css/
+        │   │   ├── admin.css
+        │   │   └── frontend.css
+        │   └── js/
+        │       ├── admin.js
+        │       └── frontend.js
+        ├── languages/
+        │   ├── wc-tier-package-prices.pot
+        │   ├── wc-tier-package-prices-de_DE.po
+        │   ├── wc-tier-package-prices-de_DE.mo
+        │   ├── wc-tier-package-prices-de_CH_informal.po
+        │   └── wc-tier-package-prices-de_CH_informal.mo
+        └── vendor/
+            └── (Twig and dependencies)
 ```
 
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