docs(readme): add bl config agent example to Configuration section

Document the one-command coding-agent setup (`bl config agent`) in the
Configuration section of both README.md and README.zh.md.

Author: lishengzxc

README.md

@@ -210,6 +210,12 @@ bl config set --key base_url --value https://dashscope-us.aliyuncs.com
 bl config set --key default_text_model --value qwen-turbo
 bl config set --key timeout --value 600
 
+# Configure a coding agent (Claude Code, Qwen Code, OpenCode, OpenClaw, Hermes, Codex)
+# to use DashScope with one command
+bl config agent --agent claude-code \
+  --base-url https://dashscope.aliyuncs.com/apps/anthropic \
+  --api-key sk-xxxxx --model qwen3-max
+
 # Self-update to latest version
 bl update
 ```

README.zh.md

@@ -208,6 +208,11 @@ bl config set --key base_url --value https://dashscope-us.aliyuncs.com
 bl config set --key default_text_model --value qwen-turbo
 bl config set --key timeout --value 600
 
+# 一键配置编程 Agent（Claude Code、Qwen Code、OpenCode、OpenClaw、Hermes、Codex）接入百炼
+bl config agent --agent claude-code \
+  --base-url https://dashscope.aliyuncs.com/apps/anthropic \
+  --api-key sk-xxxxx --model qwen3-max
+
 # 自更新到最新版本
 bl update
 ```