Add new user quick start guide to ai-code.el header comments

Author: tninja

ai-code.el

@@ -1,4 +1,4 @@
-;;; ai-code.el --- Unified interface for AI coding backends such as Claude Code, Codex CLI, Gemini CLI, Copilot CLI, Opencode, Grok CLI, Aider CLI, agent-shell, etc -*- lexical-binding: t; -*-
+;;; ai-code.el --- Unified interface for AI coding backends such as Claude Code, Codex CLI, Gemini CLI, Copilot CLI, Opencode, Grok CLI, Aider CLI, etc -*- lexical-binding: t; -*-
 
 ;; Author: Kang Tu <tninja@gmail.com>
 ;; Version: 1.51
@@ -28,6 +28,20 @@
 ;;   - Aider CLI
 ;;   - agent-shell
 ;;
+;; New User Quick Start:
+;;   1) Minimal setup:
+;;
+;;      (use-package ai-code
+;;        :config
+;;        (ai-code-set-backend 'codex)
+;;        (global-set-key (kbd "C-c a") #'ai-code-menu))
+;;
+;;   2) First 60 seconds:
+;;      - C-c a a : Start AI CLI session
+;;      - C-c a c : Ask AI to change current function/region
+;;      - C-c a q : Ask question only (no code change)
+;;      - C-c a z : Jump back to active AI session buffer
+;;
 ;; Basic configuration example:
 ;;
 ;; (use-package ai-code