Document new conflicting `claude_code_docs_map.md` behavior

Claude Code has recently (in v2.0.x something) started fetching its own docs via [`claude_code_docs_map.md`](https://code.claude.com/docs/en/claude_code_docs_map.md):

<img width="1196" height="378" alt="Image" src="https://github.com/user-attachments/assets/891fe0ab-1bed-4ab0-8faf-d7f8835c654d" />

This new feature conflicts with the `/docs` command introduced by this repository.