fix: Resolve additional dead links across documentation

- README.md: Fix blog-post link, update claude-examples to anthropic-cookbook
- LEARNING-ROADMAP.md: Update claude-examples to anthropic-cookbook
- claude_concepts_guide.md: Fix 07-hooks to 06-hooks, update skills repo
- 05-mcp/README.md: Fix MCP spec URL
- INDEX.md: Fix all 07-hooks references to 06-hooks
- .github/ISSUE_TEMPLATE/config.yml: Update claude-examples URL

LEARNING-ROADMAP.md

@@ -548,7 +548,7 @@ Once you've completed all milestones:
 - [Discovering Claude Code Slash Commands](https://medium.com/@luongnv89/discovering-claude-code-slash-commands-cdc17f0dfb29)
 
 ### Community
-- [Claude Code Examples](https://github.com/anthropic/claude-examples)
+- [Anthropic Cookbook](https://github.com/anthropics/anthropic-cookbook)
 - [MCP Servers Repository](https://github.com/modelcontextprotocol/servers)
 
 ---