Update README and address documentation feedback

## Changes

1. **Update main README**
   - Added Rspack to "What's New" section as first bullet point
   - Added Rspack to "Why React on Rails?" features table
   - Highlights ~20x faster builds with links to documentation

2. **Address comment #1: Remove redundant --no-rspack option**
   - File: docs/api-reference/generator-details.md:14
   - Removed [--no-rspack] from options list (redundant, default is false)
   - Kept only [--rspack] for clarity

3. **Address comment #2: Document switch-bundler limitations**
   - File: docs/getting-started/quick-start.md:47
   - Added detailed note about limitations in quick-start
   - File: docs/api-reference/generator-details.md
   - Added comprehensive "Limitations of bin/switch-bundler" section:
     * Custom webpack plugins not auto-updated
     * Manual updates needed for custom configs
     * Third-party webpack packages not detected
     * YAML formatting may change (but preserves functionality)
   - Cross-references to unified configuration docs

4. **TypeScript handling confirmed working**
   - Rspack uses SWC which handles TypeScript natively
   - No .ts file updates needed
   - --rspack --typescript combination works seamlessly

## Documentation Now Complete

The Rspack feature is now documented in:
- Main README (prominent placement)
- Quick Start guide (with limitations)
- Generator Details (comprehensive with limitations)
- Webpack Configuration (technical details)

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

Co-Authored-By: Claude <[email protected]>

Author: justin808

README.md

@@ -20,6 +20,7 @@
 
 **🚀 React on Rails v16.0 Released!** Major modernization with ESM support, enhanced React Server Components, and streamlined configuration.
 
+- **⚡ Rspack Support**: New `--rspack` generator flag for ~20x faster builds! Use Rspack instead of Webpack for dramatically improved build performance. See [Rspack documentation](https://www.shakacode.com/react-on-rails/docs/api/generator-details#rspack-support) for details.
 - **ESM-only package**: Modern module system with better tree-shaking and performance
 - **React Server Components**: Improved rendering flow and new `RSCRoute` component for seamless SSR
 - **Performance improvements**: New async loading strategies and optimized bundle generation
@@ -111,8 +112,9 @@ To provide a high-performance framework for integrating Ruby on Rails with React
 
 | Feature                       | Benefit                                                                                                                                                                                      |
 | ----------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
+| ⚡ **Rspack Support**         | [~20x faster builds](./docs/api-reference/generator-details.md#rspack-support) with Rspack bundler - dramatically reduce build times in development and CI                                   |
 | 🎯 **Smart Bundle Loading**   | [Automated bundle optimization](./docs/guides/auto-bundling-file-system-based-automated-bundle-generation.md) based on components used - no more manual `javascript_pack_tags` configuration |
-| ⚡ **Server-Side Rendering**  | Enhanced React Server Components support for better SEO and UX performance                                                                                                                   |
+| 🌟 **Server-Side Rendering**  | Enhanced React Server Components support for better SEO and UX performance                                                                                                                   |
 | 🚀 **Advanced Loading**       | `sync`, `async`, and `defer` options for optimal performance based on your needs                                                                                                             |
 | 🔥 **Hot Module Replacement** | Instant feedback during development with tight [Shakapacker](https://github.com/shakacode/shakapacker) integration                                                                           |
 | 📦 **Easy Props Passing**     | Direct Rails → React data flow without separate API calls                                                                                                                                    |

docs/api-reference/generator-details.md

@@ -11,7 +11,7 @@ Usage:
 Options:
   -R, [--redux], [--no-redux]                      # Install Redux package and Redux version of Hello World Example. Default: false
   -T, [--typescript], [--no-typescript]            # Generate TypeScript files and install TypeScript dependencies. Default: false
-      [--rspack], [--no-rspack]                    # Use Rspack instead of Webpack as the bundler. Default: false
+      [--rspack]                                   # Use Rspack instead of Webpack as the bundler. Default: false
       [--ignore-warnings], [--no-ignore-warnings]  # Skip warnings. Default: false
 
 Runtime options:
@@ -156,6 +156,17 @@ The switch-bundler script automatically:
 - Installs/removes appropriate dependencies
 - Works with npm, yarn, and pnpm
 
+**Limitations of `bin/switch-bundler`:**
+
+The switch-bundler utility handles the standard configuration and dependencies, but has some limitations:
+
+- **Custom webpack plugins**: Does not modify custom webpack plugins or loaders in your config files
+- **Manual updates needed**: If you have custom webpack configuration, you may need to update it to use unified patterns (see examples in [Webpack Configuration](../core-concepts/webpack-configuration.md#unified-configuration))
+- **Third-party dependencies**: Does not detect or update third-party webpack-specific packages you may have added
+- **YAML formatting**: Uses YAML.dump which may change formatting/whitespace (but preserves functionality)
+
+For apps with custom webpack configurations, review the generated config templates to understand the unified configuration patterns that work with both bundlers.
+
 **Combining with other options:**
 
 ```bash

docs/getting-started/quick-start.md

@@ -45,6 +45,8 @@ Take a look at the files created by the generator.
 - Webpack configuration
 
 > 💡 **Performance Tip:** Add the `--rspack` flag for significantly faster builds (~20x improvement). You can also switch bundlers later with `bin/switch-bundler rspack`.
+>
+> **Note on `bin/switch-bundler`:** This utility safely switches between webpack and rspack by updating `shakapacker.yml` and managing dependencies. However, it does not modify custom webpack configuration code. If you have custom webpack plugins or loaders, you may need to update those manually to work with rspack. See [Rspack documentation](../api-reference/generator-details.md#rspack-support) for details on unified configuration patterns.
 
 ## 🎯 Step 2: Start the Development Server (1 minute)