docs: add instruction for Cloudflare AI Gateway

Author: liby

docs/configuration_manual_CN.md

@@ -9,6 +9,11 @@
 
 - 可选项
 - 默认值: `https://api.openai.com`
+- 说明
+  - 自定义 API URL 可以解决服务不稳定以及 IP 被封禁的问题，切换到反向代理服务来提高稳定性，并保护我们的 IP 地址不被 OpenAI 封禁
+  - 或者是使用一些云服务商提供的 API 网关服务，比如 Cloudflare AI Gateway，除了可以代理 OpenAI 的 API 请求外，还额外增加了缓存、调用分析以及日志管理等功能
+    - 将 API URL 设置为 `https://gateway.ai.cloudflare.com/v1/${ACCOUNT_TAG}/${GATEWAY}/openai` 即可体验
+    - 更多信息请参阅 [Cloudflare AI Gateway 官方文档](https://developers.cloudflare.com/ai-gateway/)
 
 ### Dep. Name
 
@@ -64,4 +69,4 @@
 - 默认值: `translate from $sourceLang to $targetLang:/n/n $text`
 - 说明
   - 自定义 User Prompt，填写则会覆盖默认的 User Prompt
-  - 可以使用与系统指令中相同的变量
+  - 可以使用与系统指令中相同的变量

docs/configuration_manual_EN.md

@@ -9,6 +9,11 @@
 
 - Optional
 - Default value: `https://api.openai.com`
+- Description
+  - Customizing the API URL can address issues of service instability and IP bans by switching to a reverse proxy service to enhance stability and protect our IP address from being banned by OpenAI.
+  - Alternatively, using API gateway services provided by cloud vendors, such as Cloudflare AI Gateway, not only proxies OpenAI API requests but also adds extra features like caching, call analytics, and log management.
+    - Set the API URL to `https://gateway.ai.cloudflare.com/v1/${ACCOUNT_TAG}/${GATEWAY}/openai` to experience it.
+    - For more information, please refer to [Cloudflare AI Gateway Official Documentation](https://developers.cloudflare.com/ai-gateway/).
 
 ### Dep. Name
 
@@ -64,4 +69,4 @@
 - Default value: `translate from $sourceLang to $targetLang:/n/n $text`
 - Description
   - Customize User Prompt, filling this will override the default User Prompt
-  - Can use the same variables as in the system command
+  - Can use the same variables as in the system command