fix(docs): update dead Claude Code link to product page

The claude.ai/claude-code URL returns 404. Updated to use
code.claude.com which redirects to the product landing page.

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

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

Author: alexeyv

docs/index.md

@@ -38,7 +38,7 @@ These docs are organized into four sections based on what you're trying to do:
 
 BMad works with any AI coding assistant that supports custom system prompts or project context. Popular options include:
 
-- **[Claude Code](https://claude.ai/claude-code)** — Anthropic's CLI tool (recommended)
+- **[Claude Code](https://code.claude.com)** — Anthropic's CLI tool (recommended)
 - **[Cursor](https://cursor.sh)** — AI-first code editor
 - **[Windsurf](https://codeium.com/windsurf)** — Codeium's AI IDE
 - **[Roo Code](https://roocode.com)** — VS Code extension