docs: add F11 fullscreen exit instructions to FAQ

doc/FAQ-CN.md

@@ -39,3 +39,12 @@
 ```
 
 这个情况往往是因为你正在使用自己的 OpenAI 账户，你在模型中选择了 GPT-4，但 OpenAI API 账户不支持 GPT-4。截止到 2023 年 07 月 04 日，所有 OpenAI API 账户都需要向 OpenAI 填写申请后才能使用 GPT-4 模型。这里是申请链接： https://openai.com/waitlist/gpt-4-api 。请注意，即使你是 ChatGPT Plus 用户，你也需要申请后才能使用 GPT-4 的 API 模型。
+
+### 1004
+
+#### 在 Windows/Linux 下不小心按了 F11 进入全屏，怎么退出？
+
+在 Windows/Linux 桌面版中，按 **F11** 可以切换全屏模式。如果误入了全屏并且无法退出，可以通过以下任一方式恢复：
+
+- 再次按下 **F11** 键即可退出全屏。
+- 将鼠标移到**窗口顶部中间区域**，会有一个隐藏的退出按钮，点击即可退出全屏。

doc/FAQ.md

@@ -39,3 +39,12 @@ If you select GPT-4 and receive a similar error message when sending messages:
 ```
 
 This issue often occurs when you're using your own OpenAI account and have selected the GPT-4 model, but your OpenAI API account does not support GPT-4. As of July 4, 2023, all OpenAI API accounts require a request to be submitted to OpenAI before the GPT-4 model can be used. Here's the application link: https://openai.com/waitlist/gpt-4-api. Please note that even if you're a ChatGPT Plus user, you still need to apply for access to use the GPT-4 API model.
+
+### 1004
+
+#### On Windows/Linux I accidentally pressed F11 and entered fullscreen. How do I exit?
+
+On Windows/Linux desktop versions, press **F11** to toggle fullscreen mode. If you accidentally entered fullscreen and can't figure out how to exit, try one of the following:
+
+- Press **F11** again to exit fullscreen.
+- Move your mouse to the **top center area of the window** — a hidden exit button will appear. Click it to exit fullscreen.